Sea Shrine

The Underwater Temple is a temple on Earth which houses The Hourglass. It's first appearance was in "Steven and the Stevens".

About
The Underwater Temple is filled with various hourglasses. If an hourglass besides the glass of time is tampered with, the temple will become filled with water, flooding the inside. This is shown when Amethyst grabs the wrong hourglass in "Steven and the Stevens".

According to Pearl, the Underwater Temple reforms every 100 years after being flooded with water.

Trivia

 * According to Pearl, the Underwater Temple fell apart prior to "Steven and the Stevens" also.
 * The mechanic of choosing the correct hourglass is likely a reference to Indiana Jones and the Last Crusade.