Oxyale
From Final Fantasy Wiki
Oxyale is an item in Final Fantasy that is used by the player in Gaia to breathe underwater and explore the Sunken Shrine.
To obtain the item, the player must first buy the Faerie Bottle for 50,000 Gil at the Caravan, which is located in a desert west of Onrac. They must then return to Gaia and go through its maze-like wooded back area. The player should eventually find a pond. Stand by the pond and use the bottle. A fairy will appear and give you Oxyale to put in the bottle. Return to Onrac and speak to the woman in the southeast corner of the town, near the sea. She will reveal herself as a mermaid's spirit, then vanish and allow the player access to a crude barrel that serves as the submarine transport to the Sunken Shrine.
