South Kalimantan/South Borneo (Indonesian: Kalimantan Selatan often abbreviated to Kalsel) is one of the thirty-three Provinces of Indonesia and one of four Indonesian provinces in the Indonesian part of Borneo. The provincial capital is Banjarmasin. The province boundaries are with Makassar Strait in the east, Central Kalimantan in the west and north, the Java Sea in the south and a small part of East Kalimantan in the north.

The population of South Kalimantan was recorded at just over 3.625 million people at the 2010 Census. In 2008 the number of visitors to the province was 339,000 of which 21,000 were international visitors, mostly from China, Philippines and India.

About three quarters of the province is flat and less than 100m above sea level, while about 8,000 km² are swampland. The Meratus Mountains are situated approximately along the south-western part to the north-eastern part of the province, dividing the flat area into two. Its highest peak is Gunung Besar with 1,892 metres.

The annual rainfall intensity is high, ranging between 2,000 and 3,700 mm. The mean number of rainy days per year is 120. Barito is the main river, used as a transportation route to the northern part of the province and to Central Kalimantan. Other smaller rivers are mostly springing from the Meratus Mountains.