Ox Bel Ha System

A system discovered in February 1996 whose name means "three paths of water" in Yucatec Maya. As of January 2023 it was the longest underwater cave system in the world, with 435.8 km surveyed against Sac Actun's 259.5 km; the English Wikipedia gives an updated figure of 541.7 km. It has at least 160 entrance cenotes and a maximum recorded depth of around 57 m. The halocline varies between about 10 m near the coast and about 20 m inland; CINDAQ estimated that 27% of the system is salt water and 73% fresh.