How to get sea creatures?

You need to buy a wetsuit then you will be able to swim in the sea. When you see bubbles appear swim towards them. You will then see a dark shadow in the water, press y to dive and swim after it. It can take a while to catch some of them, but keep at it -

you'll catch them eventually. Like bugs and fish different ones spawn at different times of the day. Good luck 👍

You might need to “Corner” some fast movers to the outer fence limits to capture them. Keep at it!

Yep, that's exactly how I get the fast ones, If ur lazy and don't want to swim back to shore (and u don't mind spending some miles), you can call Rescue Service and they will deliver you to your home, shop, etc. Happy diving!!!

Or plan it so you close up the game after this & just press - (minus key) better still if diving with guests (& gate open) doing this doesn’t close but returns you to airport.