The Prison Island is an island connected to Illisa Bay through the Undersea Cavern. It was originally sealed off because the sea monster lived there and it was dangerous to pass. The people of Lidiera controlled the tide by closing a gate at high tide, making it impossible to traverse the underwater path to the island.
After entering the Prison Island, the party finds Lenus and realizes that the reason the Dragon, Regole, has been harmful to the surrounding area is because Lenus has been controlling it. Lloyd shows up and is given the Dagger from Lenus, explaining to the party that he is going to Mille Seseau and that they should follow him if they want to reclaim the Moon Dagger. He leaves Lenus behind to finish the party. Lenus turns into the Blue Sea Dragoon and fights the party with Regole. Once the battle is over, Lenus is happy because she gave everything to Lloyd and dies in peace. Meru is saddened by this chain of events, and the Dragoon Spirit leaves Lenus and finds its way to Meru, making her the new Dragoon Spirit holder.
 Enemy List