Ocean Biomes are one of the most difficult biomes to live in in Minecraft. A Boat is required to traverse one quickly, and players without one will have difficulty moving around much, due to both the slowing effects of the water and the fact that swimming decreases hunger faster than walking. Advanced players, however, may make a safe base out here. Ocean biomes, should the player decide to take a look at the bottom, are filled with sand and dirt, with a little bit of clay mixed in. They are the best sources of clay in the game (rivers and ponds have little, if any). Every block is a source block; there is no downward current in oceans.