Critters and creatures occupy the vast sea! Now, this one's your regular fish, preferred prey of everything! We might spent some time to get these fish some kind of swarm intelligence. E.g. they stick together and burst out when something's swimming through or so.



The crab walks around, eating this and that. Sometimes a fish! Nasty little claws do hurt when they pinch your clonk. Crabby meat is very tasty but hard to get. Crabs aren't killed that easily. Objects bounce off them, the harpoon is useless. Only a driven harpoon from the slinger can do the job (well, explosions work as well).
Crabby meat is a great bait for fishnets!



Seaweed grows everywhere! It might very long to pose for a better threat. It entangles your clonk. You will either struggle a little bit to get free or just use your knife.
Also, seaweed is the preferred hideout place for underwater creatures. Crabs and fish will try to hide in there.



Jellyfish are a real threat with their poisonous tentacles! These are very long, too. Also, shooting them with a harpoon will kill them but they continue to float around (instead of swimming), deadly as ever.



The snail doesn't do any real harm, it justs crawls around. Also, the shell is extremely tough. Only explosions kill it, so forget your harpoons and slingers. When a crab gets hold on a snail, it first eats it and then uses the shell for protection. Now you need an explosive for that crab!

Snails might walk around on clonks or submarines, making them heavier and harder to steer.



Deep down below hunts the Lurker, Horror of the Deep! You don't kill the lurker, you don't see lurker. It's a shadowy mass, sprouting tentacles in every direction. These things will smash your submarine and surely smash your clonk. Shooting a tentacle with a harpoon will fend it off but not realy harm the Lurker (just making it angrier!).
What might scare the Lurker is light. But not for long!



The nasty little spawn of the Lurker will come in hundreds! They try to eat you or try to eat through your subs hull, so better rise fast or have a knife and / or many harpoons ready!