Mermaid's Cave

Mermaid's Cave is the sixth dungeon in Oracle of Ages. It is where Link finds the Mermaid Suit and the sixth Essence of Time, the Lonely Peak. The Boss is Octogon. Out of all the dungeons in Oracle of Ages, it is considered to be the most annoying, as constant time travel is required to finish it.

The Mermaid's Cave requires two keys -in the past and present- to enter. The present key can be won by beating the Goron Dancing Game, and the Ancient Mermaid Key can be won by completing the Big Bang Game. The dungeon is found at the Rolling Ridge behind a waterfall in the past and built into a wall in the present as the waterfall has dried up.

Trivia

 * The Miniboss, Vire, is also found in Oracle of Seasons and Link's Awakening.