
The swimming animations look off to me, especially when player characters have fins.
I think the main reason for this is that said characters flail their arms around like someone who has never dove before.
In real life, experienced free divers and SCUBA divers typically dont use their arms to swim. They don’t provide much thrust compared to fins, and holding them out increases drag.
Compare the swimming animations to the ones in the game Abzu. I think Abzu’s animations look much more naturalistic because the character tends to keep their arms at their side, maintaining a streamlined profile.
I think the animations should be changed such that when characters have fins, they don’t use their arms to swim and maintain a streamlined profile.

It doesn’t have to be realistic, it’s a game

No, but I think features of the game should be immersive and follow the established rules of the game’s universe.
The swimming animations are a minor thing that break my immersion. The characters swim like novices who don’t know how to maneuver themselves in water. It looks goofy to me. I’d think people who are stuck on an ocean planet would learn how to swim efficiently.