On this page of the Valheim game guide, you will find information about the Ocean, one of the biomes found in the game. You will learn more about the resources and enemies found here.
The Ocean is the most arid of all biomes. With some exceptions, it mostly serves as a method of travelling between islands. Of course, this does not mean that it is 100% safe.
The only source of materials in the Ocean is the Leviathan. It's a huge, passive, turtle-like creature. Only the creature's shell is visible above the water surface. It resembles a small circular island, devoid of tall plants. You can walk on top of it without a problem. Hitting it with a pickaxe will extract chitin. However, you must keep in mind that after a hit, the creature will start to dive.
The main threat that awaits you at sea is the Serpent. This is a sizable water snake that you may come across while sailing. It deals a lot of damage – the creature can easily destroy your boat. In order to eliminate the opponent, you must use the bow. However, it will still be quite a challenge - this enemy has a large number of life points.
However, if you are defeated by a serpent, then you have a chance to retrieve your possessions. There is a small chance that the enemy will be near the spot where you died.