Bubbles on the water.

[Rastachka]

I suggest making bubbles on the water.

When a character drowns, depending on the level of his clothes, a certain number of bubbles appear on the water.
The greasier the clothes, the bigger the bubbles. This spot lasts for a while, and after some time has passed, other players will be able to catch it.

What does it give? Ha! It's up to you.