Sea creature
From Nookipedia, the Animal Crossing wiki
Deep sea creatures are a new category of collectables in Animal Crossing: New Leaf, found by diving underwater while swimming. Both Octopuses and Lobsters are now deep sea creatures, as opposed to fish obtained by fishing in previous installments of Animal Crossing series. To catch any deep sea creatures, the player must have a wetsuit, either purchased from Tortimer Island or rented from Lloid.
