It is located in Renbow Waters (Japanese: レインボじまのおきOff the Coast of Rainbo Island) south of Renbow Island and can be accessed by riding Lapras from Lapras Beach. When the player first enters Coral Sea they will be required to find a UFO. It is possible to go here anytime after getting the UFO by talking to Nixie who will let the player ride Lapras to the Coral sea. There are some missions which require the player to go here to complete.
In the Coral Sea there are four areas: the Uppermost Area, the Middle Area, To the Depths Passage, and the Dark Area. Each of these has different Pokémon and obstacles.
The player comes out here when the player jumps off Lapras, this also were the player may go back to the beach. This is a simple area with rock walls making a channel leading to the next area.
This area is much larger than the Uppermost Area. It starts at the end of the rock channel right near a current. This current the player can swim against but will move at very slow speeds, it tries to sweep the player along when he tries to exit the current. When the player first comes here, near the bottom of this area, there is a very strong current that when the player tries to swim through his Styler informs him that it is too strong, and he bounces back. To the right there is another area with a Corsola which the player can use to knock down a rock to block the current. Pokémon are most plentiful in this area.
This area is completely dark except the area around the player. This area is very small, but the more Chinchou the player has with him the more light there is around him. The only other light is yellow from wild Chinchou's bulbs, and red from Sharpedo's eyes and the UFO. The player has to fight angry Sharpedo when he first comes here and collects the UFO.