What does this death message mean?

This death message is a very rare one, that can be triggered by using a Trident with the "Riptide" enchantment. It is caused by riptiding (from under the ocean) to a high altitude, then riptiding downwards while falling back into the ocean. But he said that he was swimming down to a shipwreck, right? Which means that either there is another way to trigger this death message, or that he is lying.

This is the "official" way to recreate this death message:

1. Make sure you are fully submerged in the ocean and it is raining.
2. Using your Trident with the Riptide enchantment, riptide upwards.
3. Keep riptiding until you reach an extremely high altitude (like 5000 or 6000 blocks)
4. Then, while you fall back into the ocean, riptide downwards back into the ocean.
5. When you hit the ocean floor, this death message should appear.

Another theory is that a server glitch, or a troller, teleported him to a high altitude. Then as he fell, he riptided downwards and hit the ocean floor.

Or maybe the server intended it to show this death message upon doing something.

There are a lot of ways this death message can appear. These are just my theories.

Hope I helped...

What it means is when your surver is lagging but it doesn't seem like it is and you fall off of a cliff but don't take that damage until later when you are swimming around you take the damage that you would of took when you fell later in the water. Don't really know what is the cause if it is that makes this happen sorry.

Hope that is helpful.