Biotic compatibility

Actually, having a good climate but no life is not that bad. Alien life almost always has different biochemical properties, such as chirality, which make it unusable for human usage and consumption. In order to grow Terran crops, you will need to completely replace the soil in a large area, destroying the native ecosystem. After all, not the native creatures are aliens. WE are the aliens in this case.

On a lifeless planet, you don’t need to do any of that. You just need to regularly bring humus and seeds from Earth. Or, if there is no contact, put enough of that on your ship. You can bring various animals and plants and immediately start building a Terran ecosystem from scratch, without having to worry about tasty but diarrhea-causing fruits, irritated natives, or worse, disgusting monsters and predators.

Living near a coast is advantageous for many reasons, some of them described in the previous answers. You could build a desalinization plant and use the seawater for irrigation. If there are serious tides, you can close off a bay or a fjord and build a power plant. And finally, the climate is usually best near the sea, which functions as a thermal mediator, fixating heat during the day and dissipating it during the night. The further you go from the coast, the more severe become the temperature variations between day and night. This is bad for humans and all animals and plants participating in the mission (unless they are native to deserts, but I doubt that you want to do that).

If you are afraid of flooding or extreme tides, you can always build dykes.

To have rapid access to radiation shielding

Solar radiation is a problem on earth, but we deal with it pretty easily. We put a roof over our heads, we wear sunscreen, trees protect us. But every so often, the sun spits out a bunch of high energy protons directly at us. There are also random gamma bursts from mysterious stellar objects.

Water does an excellent job of blocking this radiation, a meter of water can reduce a gamma burst to less than 1%, and 2 meters to 1% of 1%. 10 meters of water is typically used to block neutron and proton radiation in nuclear reactors, and should be sufficient against a devastating CME.

Your area of space may be filled with known and unknown hazardous radiation sources, and you need to be protected, either by building your colony underwater, pumping water to land and covering your colony with it, or having panic rooms in the ocean that you can quickly get into from land. Underground bunkers would work, but a planet without life is probably a planet without dirt, and you would need to bore directly into rock, a very high energy process requiring lots of resources like drilling rigs and bits.

Continually keeping several meters of water on top of an aboveground colony seems like a bad idea, failure of the dome can kill everyone, and the engineering cost sounds quite high to me.

Having your colony be submerged all the time is also expensive, more exotic coatings are required to protect against corrosion due to constant exposure, and the structural integrity of the buildings requires specific design and lots of material. Submersion only when needed still requires designs that an withstand the pressure.

A panic room setup is more reasonable, there is a smaller structure with a tram or some other high speed transport to take you through a tunnel into the submerged area, and the aboveground side of the tunnel is in the center of the colony for rapid evacuation. You could even have automated evacuation, people sleeping in their beds are enveloped in a small craft and literally dumped into a pneumatic tube. There may not be a lot of time to take shelter.

Lot of good answers already. Perhaps one to add is that starting terraforming may be easier done in water. I mean that's how it worked the first time round.

I would like to think, that if one is planning a self-sufficient colony on another planet, then you would take everything you would need in order to survive on the planet. The colonist will also have knowledge of why the planet is lifeless

We will likely have some sort of water purification device in case of non-potable water at the source (likely). If the land is arable, we not only have the means to start agriculture, but the ability to irrigate via the waters nearby ... hopefully. Also, some device to ensure or manufacture soil fertility. We may just skip the dirt and start with hydroponics. There are options. Depending on the technology level, some form of mining automatons could get us the raw martials needed to expand.

The colony ship itself is likely set up to be able to be lived in for the medium term while the colony is begun. I would expect it to be able to not only survive the space trip but to be able to be used for a good time as a terrestial dwelling.

Overall, a coastline landing site provides the best chance for a large quantity of both water and land with which to work with.

One interesting, but unmentioned point is that by aiming for the coatline, you can land the ship either on the land or in the water. The land might not be conducive to both landing the colony ship on it and using it as a base of operations to spread out from.

In addition, it might be decided at the point of arrival, that the colony will begin underwater due to changes in the information about the planet since arrival. While that provides its own challenges, the water may also provide critical shielding from certain things above.

Remember, the sun is a deadly laser.

All the industries like Power Generation, cloth manufacturing you name it, need a large amount of water

[Pardon me addressing the OP as “you”; I think it is all going to sound rather contrived otherwise.]

[I suggest searching “terraforming” on this site. I found this:
https://worldbuilding.stackexchange.com/questions/165596/an-earth-like-planet-is-found-in-another-solar-system-what-are-the-top-prioriti/165600#165600 .]

[I am taking it that you want the colonists to settle near the coast.]

They will probably settle where they arrive. Conversely, I take it they came in from space, so they (presumably) could and would have chosen where to land/settle. (Conversely again, having a very good idea of all the pro’s and con’s tends towards high suspension of disbelief.)
Human beings have been short-sighted in their built-infrastructure planning for the whole of human existence. (Examples: • building on farmable land and • putting traffic lights at/under freeway overpasses.) I think that the reason is that planning well takes so much additional time and work. Conversely, this particular case is (presumably) very thoroughly planned (“money no object”).

I take it that the oceans and rivers are H2O (and that they were able to establish this). A quick Google search reveals that ocean salt comes from rocks, so the ocean will be salty.

The governing factor is that (presumably) the spaceship must have been able to support all the people on board for decades — meaning that it is a functioning closed system. (The spaceship would have been designed with a power source with extra capacity, for when they came to setting themselves up on their new planet.) It is tempting to think that they would race out of the spaceship and start madly working on surviving on the new planet. I am sure that they would work hard on making the planet support (their) life, but there is no danger nor deadline involved.

The point is that the absolutely crucial thing is landing the spaceship somewhere where it will be safe and useful, to the very highest possible level of certainty. It would remain their home for months to years.

Other people have suggested reasons for setting up on the coast. I would like to suggest that landing the spaceship on or very near the beach is a very reliable way of rusting it away in literally a year or two, or a decade or two, depending on the distance. Near the coast is much more sensible.

(One pivotal issue is that of whether or not the planet’s air is breathable, or whether they have to use space suits. I take it that, in this case, it is. I think it would be foolhardy, nonetheless, to allow any of the planet’s air into the spaceship, nor to breathe any of it, until it has been thoroughly checked. This is a short-term issue, unless you want the story to be that the air, or the environment generally, is unsafe.)

I am thinking that they will have a long-term plan to “multiply and fill the earth”, and that this would govern their priorities. I am no expert, but I am fairly confident that the main first thing would be to get farming going. They would certainly use water from the planet, not from the spaceship, for this farming.

Arable soil is not just dirt; Earth dirt [that will support plants] is/supports a complex ecosystem. If this planet is lifeless, the soil is going to be lifeless. (Actually, there might not be soil; you would have to ask someone else. [I would guess, from “The Martian”, that any dust can be soil.]) Either way, there is masses of work involved in getting farming going.

Normally, a flood plain is the best place for crops. Under these artificial conditions, it might not be; I do not know. Either way, I would expect them to look for a large flattish area near water (a large lake or river)… with a secure, flat, sheltered spot nearby for the spaceship.

Short- to medium-term, they want mineral resources nearby.

I do agree that being near the ocean seems like a good idea, but I would consider that a long-term issue. (They would want to seed the ocean with fish, I would think. Unfortunately, the smallest fish eat something other than fish, so that is a long-term project.) Finding a fully ideal spot would be radically unlikely. (As I said) I think that their initial site would be governed… medium- to large-scale, by available minerals, and small-scale by setting up farming.

I can not see them building a desalination plant. They might well have one on the spaceship. Nonetheless, I can not think of a compelling reason for them to have to set up near the ocean and run a desalination plant, short of there being no rivers. (Some rivers on Earth are unreliable in some years, but I think there are some that are reliable.)

I suppose the conclusion is that landing somewhat near the coast is desirable long-term — notably for access to [the] other minerals (and long-term they might set up other colonies with different plant ecosystems, and thus resources) — and that it is no stretch for your story to supply a suitable spot that is near the coast.

Landmark (this is a good oxymoron)

Normally when playing survival games , I like to settle on the coast because its the edge of land. it gives u a landmark for navigation.

Safety

Usually when humans use the ocean, there are boats involved. this keeps them safe from most water creatures and hazards. anchoring can be used to keep away from rocks and repairs/emergency procedures can keep up with harsh weather. Hazards on the land such as volcanoes, are usually avoidable if u have a backup plan on the ocean-side.

if any other people become tribal (thus warring for resources) or infected with some kind of infectious disease, being near the ocean can provide quick access to a safe haven or quarantined area

Large bodies of waters act as heat sinks i.e. they tend to moderate temperature differences and atmospheric moisture content over land in the immediate vicinity of the body of water in question.

For the most part deserts (allowing for local prevailing wind patterns) are on Earth located in the interior regions of continents, far away from large bodies of water. As a result they tend to have larger/more extreme temperature cycles than other regions i.e. they have on average a far hotter day time temperature and a far colder night time temperature than other regions closer to water and are generally less habitable as a result.

Put simply water absorbs heat better than rock/soil does and then releases it at a stable rate. A colony placed close to an ocean (doesn't have to be ON the shoreline BTW) of a lifeless world will experience less severe climatic extremes and higher atmospheric moisture content than one placed in the center of a continental land mass. That greatly assists with any transforming operations your colonists want to undertake.

Other people have already covered the benefits of wind power, water, transport, terraforming, and climate, but there is one more big reason.

leisure activity

Oceans and beaches have high entertainment/leisure value, swimming, surfing, games, ect. Beach activities tend to be low on material demands thus easy to do without diverting resources and happy colonists are productive colonists.

If you have your choice of sites why would you not choose one that also helps keep your colonists happy. Keep in mind there is nothing stopping you from picking a pace where a major river meets the ocean, so you have ample freshwater on top of all the other benefits.

I propose that you would live by an ocean initially so that you could being biological teraforming.

In addtion to things mentioned already such as:

• Ease of navigation and transport by water (road and rails all need building, seas & rivers do not)
• Access to a water source for industrial processes such as cooling
• Access to an ocean for the dumping of waste materials (animal or industrial)
• Access to water for consumption (although a fresh water river would be a much better source to save the power of desalination and even better if you can move large boats up river to expand your harvestable resource area)

Although your planet is reasonably earth like at the moment it is unlikley to have a source of Oxigen without a biological process to produice it. A very easy way to make a lot of biologyical material is to seed the oceans with life. Currents will allow the lifeforms to rabidly spread far and wide much faster than they are likely to do in or on the surface of soil.

Your planet may have a breathable atmospher initially by luck but Oxigen is a highly reactive chemical. It will be depleted by chemical processes quite quickly until it is something more stable (like CO2). The main process of generating Oxigen on Earth is through biological actions that transform CO2 into C and O. Plants, baceria and plankton all can do this to some degree. Your planet likely has a water cycle already but without an Oxigen cycle it will soon (in geological terms) not have a beathable atmosphere.

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This answer was inspired by the thead of comments with @MSalters & @JamesQF

Long distance transport is cheap by water

This is true in Earth and any Earth like planet.

You are worried that is no other colonies when talking about your initial colony. So, there be will other colonies, and soon.

Why build your inicial colony with no consideration of this?

The colony's space transport is large (for some value of 'large'). There was no guarantee that the distant world would have a flat area large enough for the transport, plus the stresses from sitting on spindly legs under gravity are different from the stresses of space travel, so the transport is designed to float on or in water. The colony is established on the nearest inhabitable land.

The absence of life forms might be a bonus since the transport wouldn't kill anything during landing (nor if it can and does take off again).

Tidal Power - possibly not as a main power source, but it certainly provides a useful backup for emergencies, especially when paired with suitable batteries. It is more consistent and predictable than wind power, and better spread out throughout the day than Solar power.

While I can agree that settling near fresh water has its advantages, I envision your world/planet to be one in which the colonists bring technology with them--so settling on the coast, in my view, would be preferable to literally anything else.

As mentioned by others, coastal civilization offers the following:

- Multiple means of trade/travel:

If we're thinking of settling, which means thinking for the foreseeable future, that means being a vital port of trade and travel. Many (though not all, of course) of Earth's largest and most successful cities are on the ocean or have close river access to an ocean. This offers the benefit of trade and transport via land and water.

Aside: We can attribute much of coastal development to marine life for food but as you have said, fish aren't there... yet. Marine (and land) life should be part of a colonization plan. If not for food, wildlife should be integrated with the ocean (and land) for natural regulation of the water covering the planet. Yes, the planet is habitable now, but will it stay that way without wildlife to participate in temperature/chemical stabilization? Many nature documentaries (recent example Our Planet, Netflix) discuss the role living creatures have on regulating changes made by the planet. For this reason, I'm thinking if colonists don't bring wildlife along, they need to plan for planetary stabilization by technological means.

- Access to water, regardless of drinkability:

It would be unwise for colonists to settle another planet without plans for processing water into a drinkable form. Ocean water is terrible for us and our colonists should know that even without contact with Earth. There's a fair chance that most bodies of water in the universe are not safe for us.

- Help with industry:

Industrial cooling--yes; waste dumping--I hope not! Colonists could quickly destabilize the planet's uninhabited (and eventually inhabited) oceans by dumping waste; tourism (unavoidable! see eps answer:

 > Humans are drawn to water as a basic instinct

Coasts aside, we also love to build/develop by lakes and rivers--people love water probably because we know it's something we need--even when we can't drink it. We enjoy to be near water and live near it. Tourism will inevitably be a future industry and bodies of water will support that industry.

- Climate regulation/comfort: *

Coastal cities have the added benefit of temperature regulation. Differences in daytime and nighttime temperatures are smaller in settlements near oceans. Coastal cities tend to experience more precipitation (which can be a fresh water source, but should be a backup since colonists should be prepared to harvest and process whatever water they find). Coastal cities experience ocean breezes that drastically improve comfort. There is a huge difference in the feeling of 90 degrees in Miami (on the ocean) and Orlando (central Florida--not even that far from the ocean, but still a noticeable difference).

Presence of moisture also promotes stability when flooding occurs. If you settle in a dry area, precipitation (though rarer) has no place to go and causes more destructive flash floods. Wetter, coastal areas usually have enough moist, less packed soil to absorb floodwaters at a manageable rate. Keep in mind, paving over this wet soil will negate that water absorption (see: Houston flooding from Hurrican Harvey (https://en.wikipedia.org/wiki/Hurricane_Harvey#Houston_metropolitan_area_flooding))

*Depending on proximity to the planet's poles and nearby landmasses, hurricanes/typhoons could be an issue. (https://en.wikipedia.org/wiki/Tropical_cyclone)) See: American Southeast getting hurricanes formed near West Africa; Asia getting typhoons from the open ocean; Central America experiencing El Niños (desert meets ocean)

Your colonists may not know these things because they don't have contact with Earth, as you mentioned. But I do hope the colonists have a sort of knowledge base with which to make these decisions. Again, I can agree with developing near any body of water to be a viable option--settlements should absolutely be near some form of water. That said, being on the oceans offers more advantages than disadvantages with preparation and planning.

One last thing I would take into account: type of bedrock on the coast. Some coastal areas (Florida again, for instance) sit on less dense, less stable limestone which prohibits a lot of underground and mega-tall development (https://en.wikipedia.org/wiki/Geology_of_Florida). On the other hand, New York City sits on very thick, dense bedrock that allows for construction of both large skyscrapers and vast underground public transit, sewage, and communications systems (http://www.classichistory.net/archives/nyc-bedrock ; https://www.forbes.com/sites/davidbressan/2020/05/27/how-geology-shaped-new-york-citys-skyline/)

Also, Aquifers--the great hidden fresh water source! (https://pubs.usgs.gov/ha/ha730/ch_a/gif/A004_us.gif)

It's your Earth-like planet, so your rules!

Lifeless planet has no oxygen in the atmosphere. To manufacture it, you need energy (supposedly solar) and water. So beach (lake or ocean) would be prime place to start a colony.

There's some good answers here but there's an even more fundamental thing going on than has been discussed thus far:

Humans are drawn to water as a basic instinct

Basically from every angle (anthropological studies, psychological studies, sociological studies, brain studies, etc etc etc) the evidence is clear and conclusive: humans (as a whole, obviously there are individual exceptions) like being near water and will seek it out whenever possible. It is something that is almost certainly driven by genetics and evolution, but it goes beyond that even.

https://www.salon.com/2014/07/19/why_our_brains_love_the_ocean_science_explains_what_draws_humans_to_the_sea/

http://www.tlu.ee/~arro/Happy%20Space%20EKA%202014/blue%20space,%20health%20and%20wellbeing.pdf

Future Considerations

I would say there isn't a great reason your new colony would set up shop there AT FIRST. A large river would be better, or something like a freshwater Great Lake. You still get access to all the water you'd need for hydro, you'd be able to see the flood planes and plan accordingly, and a large enough river isn't going to just dry out on you. Plus it's freshwater, no desalinization needed! Pick one a couple hundred miles inland near the equator, and you can be guaranteed (as much as anything can be) stable climes. An oceanfront colony has most of those advantages, but the downside of your colonists rolling the dice on whether they are set up in Hurricane ally.

That being said, your colonists are here for the long haul! Their children's children's children will live on this world, maybe a second wave of colonists is expected at some point. A city by the sea would enable it to become a center of trade. There's no life yet, but seeding the planet with plankton and fish and whatnot will happen in time, and at that point your colony is placed to exploit that future resource. If you can judge the hurricane season correctly you can avoid picking a spot prone to them, and the life is good!

The coasts are the only place level enough to build.

Depicted: google maps terrain shot of the coast of Greenland.

In your lifeless world, the terrain is rugged and steep. If you go inland any distance you are hugging the side of a mountain. Only on the coasts where the ocean has weathered the rocks can you find land that is somewhat level.

1. Easy access to water.

2. Easy access to water for waste dumping.

3. Easy access to water for industrial cooling.

4. Trade by ship.

5. Easy access to ocean based mines.

6. Pleasure in beach lounging.

Water has a high specific heat. Consequently, the more water that is near a place, the more even the temperatures are. Deserts are notoriously burning hot in the day and freezing at night, but even places not far inland often see greater temperature swings than the shore.

Against this there is the effect of more precipitation.

On average, 44 % of total water abstraction in Europe is used for agriculture, 40 % for industry and energy production (cooling in power plants), and 15 % for public water supply. The main water consumption sectors are irrigation, urban, and manufacturing industry. Water use by sectors

You need water for industrial processes.
Agriculture in the colony may represent a much smaller percentage due to small initial population and probably better growing systems.
Energy production won't be significant directly (I supposed the colonists will not use hydroelectrics) but water is a very useful coolant. Cheap too if abundant.
Industrial production will have a much higher percentage though because you have to build all the necessary structures and tools for your budding colony.

There might not be life on the planet, but your crew is alive, and to stay alive they need water.

Proximity to the ocean will ensure availability of water which will surely need some refinement to be made drinkable and usable for other purposes, but which is for sure way easier than having to search for water in places like the outback or the Sahara desert. Don't forget that thermodynamics holds all over the universe, and whatever system they are using they need to dump heat somewhere.

From the scientific point of view, moreover, proximity to the ocean ensures a better capability of exploring the early origin of life.

I can think of two reasons:

• Access to drinkable water. If the oceans are salty or dirty, the settlers might establish desalinisation and/or water purifying plant (assuming today's technological level).
• Travel and cargo transport. Assuming the settlers don't have hovercrafts or helicopters, if the landscape is untamed, it would most likely be easier to travel long distances (for exploration in initial stages, and for trade latter on) via waterways, than to construct roads, let alone railroads. Transport of sizeable cargo (from mining camp, forest, or stone quarry, for example) would certainly be easier by boat.