The lake is divided into three distinct parts. The southern part opens by a 380 m wide strait to the Gulf of Thailand at the city of Songkhla, and contains brackish water of about half the salinity of the ocean. Further north after a bottleneck of only 6 km width is the Thale Luang (782.80 km²), and finally at the northern end in between a mangrove swamp the 28 km² small Thale Noi in Phatthalung Province. The most striking feature is the long 75 km long spit which separates the lake from the sea. Unlike most spits, it is probably formed when originally existing islands became interconnected by the silting from the lake precursor.