Sea creatures can be found by diving into the water in a wetsuit. You can borrow a wetsuit on the island, or buy your own (on some days) for 40 medals.
This table lists all of the different sea creatures, along with their sale price in bells. Some creatures are worth a lot more than others, but collecting them is less profitable by time than bug catching.
|Spotted Garden Eel||600|
Prices will vary based on a few factors: