Sistema Sac Actun

Sistema Sac Actun (from Spanish and Yucatec Maya meaning "White Cave System") is an underwater cave system situated along the Caribbean coast of the Yucatán Peninsula with passages to the north and west of the village of Tulum. Exploration started from Gran Cenote west of Tulum. The whole of the explored cave system lies within the Municipality of Tulum (state of Quintana Roo). In early 2007, the underwater cave Sistema Nohoch Nah Chich was connected into and subsumed into Sac Actun making it the longest surveyed underwater cave system in the world. Sac Actun measured (after connecting Sistema Aktun Hu with in January 2011) and is as of May 2017 with an explored length of only surpassed by Sistema Ox Bel Ha at . Since early 2007, these two caves frequently exchanged the title of the longest Quintana Roo Speleological Survey underwater cave system in the world. Including connected dry caves makes Sistema Sac Actun with the longest cave in Mexico and the second longest worldwide.