Ficus superba is a small island fig, a specialist which can grow on rocks and is able to resist strong winds.
The photos below show that Ficus superba is locally abundant on the small island of Pulau Datu approx 100 km by road due south of Banjarmasin in South Kalimantan.
Pulau Datu is a popular local tourist site for pilgrims visiting the grave of a local islamic preacher Datu Pamulutan.
Pulau Datu is about one kilometer offshore from the fishing village based at Tanjung Dewa and local boatmen ferry visitors to the island.
The presence of the Datu Pamulutan’s grave on the island has meant that the original island vegetation has been preserved intact.
Tg Dewa is five km north of a long sandy beach which marks the southern tip of the island of Borneo.
See here for an article on Ficus drupacea growing on the northern tip of Borneo.
Thanks to Rahim idris and Google Maps for information and photos.