The Mermaid's Cave is the sixth dungeon in Oracle of Ages. It is located at the base of the Rolling Ridge. Link traverses this dungeon both in the Past as well as in the Present, making it unique amongst the dungeons featured within the game. Link does battle with the miniboss, Vire (an agent of Veran), midway through the dungeon. At the climax of the dungeon, Link faces off with the boss, Octogon, where he impeccably uses the dungeon item, the Mermaid Suit, to come out on top. Link receives the Bereft Peak, the sixth of the Essences of Time, as well as a Heart Container for his victory. Since this dungeon is accessible in both the Past and the Present, Link needs two keys to access the entire Dungeon: the Mermaid Key, for the past, and the Old Mermaid Key for the present.
"It is a proud, lonely spirit that remains stalwart, even in trying times."
The Bereft Peak is the sixth Essence of Time, obtained at the end of the Mermaid's Cave.