The region hosts a stunning 358 submerged cave systems, representing some 1,400 kilometres (870 miles) of flooded freshwater tunnels hidden under the surface.
Near the beach resort of Tulum, the group found that the cave system known as Sac Actun once measured at 263 km, communicated with the 83-km Dos Ojos system. For that reason, Sac Actun now absorbs Dos Ojos.
"This immense cave represents the most important submerged archaeological site in the world. It allows us to appreciate much more clearly how the rituals, the pilgrimage sites and ultimately the great pre-Hispanic settlements that we know emerged," says underwater archaeologist Guillermo de Anda from Mexico's National Institute of Anthropology and History.
"It has more than a hundred archaeological contexts, among which are evidence of the first settlers of America, as well as extinct fauna and, of course, the Maya culture," he added.
The Yucatan Peninsula, where the cave is located, reportedly still holds treasures from the ancient Mayan community.