The Karimata Strait is the wide strait that connects the South China Sea to the Java Sea, between the islands of Sumatra and Borneo in Indonesia.

The strait is about 150 km wide, as measured from Borneo to the island of Belitung. Belitung is separated from Bangka Island to the east by the Gaspar Strait. Bangka lies close to the east coast of Sumatra, separated by the Bangka Strait. The Karimata islands lie in the strait, northeast of Belitung and closer to Borneo.