The South Sea Island is a tropical island located in the South Seas, a location in Kirby: Right Back at Ya!. It is home to Mosugaba and the Island Sisters and only appears in the episode, Caterpillar Thriller.
The South Sea Island is tropical in climate, as said before. It is mainly made up of tropical rain forests with lots of flowers as well as grasslands on the inside of what appears to be a giant crater. Given its rocky nature and shape, it is likely to be the caldera of a long-extinct undersea volcano. The Island Sisters make their home on one of the flowers on the island. Nightmare Enterprises kidnapped the Island Sisters from the flower they were just singing for Mosugaba in, and Mosugaba, hearing their song from the long distance from King Dedede's castle, left the island to swim across the ocean to the beaches of Cappy Town to rescue them. With the help of Kirby and his friends, Mosugaba was reunited with the Island Sisters, and they all returned home to the South Sea Island.