Which cave system in Mexico is the longest underwater cave in the world?

Which cave system in Mexico is the longest underwater cave in the world? The answer is Sistema Ox Bel Ha. Located in Quintana Roo, Mexico, it is currently the longest explored underwater cave system in the world.

The system consists of flooded limestone passages connected through numerous cenotes on the Yucatán Peninsula. Its explored underwater passages extend for more than 500 kilometres.

Ox Bel Ha has been mapped and extended through continuing cave-diving exploration. Because new passages are surveyed over time, rankings and measured lengths can change.

Sistema Sac Actun was previously described as the world's longest underwater cave system and remains one of the largest. However, current English-language reference information places Ox Bel Ha ahead of Sac Actun, so the stored answer is no longer current.