South Button Island National Park, National park in Andaman and Nicobar Islands, India.

South Button Island National Park is a tiny national park in the Andaman and Nicobar Islands surrounded by coral reefs. The protected area shields a small strip of land in the middle of the Bay of Bengal.

South Button Island is the smallest national park in India, covering about 5 km². It is one of three Button Islands — with North Button and Middle Button — that together form part of Rani Jhansi Marine National Park off South Andaman Island. The sources record no date for its designation, only its status within that marine park.

The island's name comes from its button-like shape, shared with North Button and Middle Button. The edible-nest swiftlet that breeds here builds its nest from saliva; these nests are the base of bird's-nest soup, a prized dish in Chinese cooking, which is why the species is harvested elsewhere in Southeast Asia.

Visitors reach the park by motorboat departing from Havelock Island. The best time to visit is between December and March when weather conditions are most stable.

The island hosts an endemic subspecies of the edible-nest swiftlet (Aerodramus fuciphagus), not the grey-rumped swiftlet. It is also a breeding site for sea turtles and supports the white-bellied sea eagle (Haliaeetus leucogaster).