Pirate island is a faux island located in the Sea of Mermaids in Grandia. When the mermaids who inhabit the sea wish to lure men to their death the island rises from the ocean. The island is comprised of pathways made from of ice and parts of destroyed ships.
While sailing towards East Elencia, Justin and Feena hit a young girl who is adrift at sea. The young girl, who is infatuated with Justin tells of how her entire island was taken captive by rogue pirates. Taken in by the story, Justin sets out to find the pirates and docks at the icy island.
Feena grows suspicious of the girl and doesn't trust her story, ignoring this Justin leads the way through the island while the young girl waits by the Sea Dragon. After reaching a land mass in the centre of the island, the party encounter four more girls, identical to the one seen before. The girls thank their 'Hero' Justin and explain that their is one more sister captive in a small cave.
Despite Feena's protests, Justin enters the cave and finds a single solitary girl who reveals herself to be a mermaid who is waiting for her food to arrive. The mermaid transforms into the Grinwhale and attacks the party. After defeating the monster, the island begins to sink. Justin and Feena reach the Sea Dragon just in time to see the island sink to the bottom of the ocean.