Coco's Castle is located in the South Pacific Ocean Kingdom. After Gaito's defeat, Coco returns to rebuild along with the mermaids of her kingdom. The whole kingdom is gold, with pyramids-shaped domes based on Angkor Wat. Coco's room is in the highest tower of the Castle, with a balcony that has a yellow chair with yellow star-shaped cushions.
The castle was featured in Mermaid Melody Pure Episode 12.