The King's Chamber is a locked room in Valka Castle, which can be found in Endless Ocean: Blue World's Ciceros Strait. The player unlocks it after finding the key to the room sitting on the throne at the end of the Mermaid's Ballroom, which is 'guarded' by a Luna Lionfish. It contains a desk, a table, a fireplace, and several large bookshelves lining the Western wall (in which a very rare book can be found, if the player uses the Multisensor). It also contains one of the Okeanos Tablets, which sits on the desk in the centre of the room.
The payer can access the Secret Room from this area, once they discover the hidden switch that unlocks the secret door behind one of the bookcases. The Secret Room is home to many treasures, as well as several shoals of tropical fish.
At one point in the storyline, the player and Oceana become trapped in this room for a few minutes once a passing North Atlantic Right Whale sings the Song of Dragons. However, after strategically pulling a set of levers, the door unlocks itself and the player can escape with their findings.