Ocean

The  is a large, deep body of water that spawns at both ends of a world.

Overview
You can tell that you are close to the Ocean when the background changes to sparse green mountains that appear to be mostly submerged in water. Oceans will always reach the end of the map (though usually not past it).

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When you reach the Ocean proper, the ground will almost always change to sand (though, unlike Deserts, there will not necessarily be Cacti) and will rapidly drop off into water. Any submerged sand blocks may have Coral growing on them.

Chests found at the bottom of the Ocean tend to contain water-related items such as Breathing Reeds, Flippers, or Tridents more often than chests in other biomes.

Monsters
Mobs exclusive to the Ocean include:


 * Pink Jellyfish;
 * Squids
 * Crabs;
 * Sharks;
 * Sea Snails;
 * Orcas (Console Version)

Oceans are also far enough away from spawn that it is possible for Goblin Scouts to appear in or around them, as well.

Artificial Oceans
Through experimentation, it has been determined that it is possible to create a fully functional artificial ocean. For an area to be considered an ocean, it must meet the following requirements:
 * Have a floor of sand at least one block thick.
 * At least one block of water.
 * Must be at least 1/3 of the way from spawn. [confirmation on distance?]

Bugs

 * On rare occasions, the map stops but allows you to go on, thus being able to travel to the underworld without digging.
 * Occasionally, the water on the very edge of the map may become "stuck", and will only be viewable with third party tools.
 * When walking down to the bottom of the ocean occasionally you will take suffocation damage when using Hermes Boots, even with a full Breath Meter.
 * Sometimes, although very rare, the water will not spawn. Instead, a very large and open cave is in its place. This appears to only happen on iOS versions of the game