Temple of the Ocean King

The Temple of the Ocean King, located on Mercay Island is the primary dungeon in The Legend of Zelda: Phantom Hourglass. It is visited five times over the course of the game, each time requiring the player to go deeper into it. After the first dungeon is complete, Link obtains the Phantom Hourglass on the first floor, allowing him to spend time in the temple without taking damage. Each time Link goes to the Sea King's Temple, with the exception of the third time and the last time, he does so in search of a Sea Chart. There are three enemies found in the dungeon: the Phantom Guards, Phantom Eyes, which alert the Phantom Guards to where Link is and impede his movement, and Wizrobes, which will take 15 seconds off of Link's timer if they manage to hit him. There are a total of thirteen floors in the area.

Each time Link goes through the area, he must redo all of the puzzles. However, because of the new items he has obtained, it won't take as long to go through some floors, and other floors he can skip entirely.

After the game is beaten, the player may participate in a time trial within the dungeon. At the end, they are awarded with two boat parts. The rarity is determined by how much time is remaining. Because of the many golden pots scattered across the dungeon, which, when broken, give Link more time, as well as the time received after defeating Wizrobes, it is possible to clear the dungeon with the Phantom Hourglass full at the end.

After the fourth dungeon is cleared, Oshus reveals that he is actually the Ocean King himself. He was sealed by Bellum, but created the alter ego of Oshus. The Ocean King explains that Bellum dwells on the final floor of the temple, absorbing more and more Force.