The Dos Ojos are one of several underwater cave systems in Mexico and an absolutely unforgettable experience for cave divers! In the state of Quintana Roo alone, the total length of explored caves is close to 1,000 kilometres.
Dos Ojos translates as "Two Eyes" and refers to a globally unique sight in Mexico, which is also on our list of the top 10 sights in Mexico. The Dos Ojos cave system, which is extremely popular with divers, has a length of about 82km, unites 28 so-called "cenotes" and is thus the third largest underwater cave system in the world after Sistema Ox Bel Ha and Sistema Sac Actun.
The latter is only 6 metres away from the Dos Ojos at its closest distance. In August 2012, a connection was discovered between the Dos Ojos and the Sac Actun, which leads through a dry passage. The Sac Actun/Dos Ojos cave system thus reaches a length of 311km, making it the second longest cave in the world after Mammoth Cave in the US state of Kentucky.
In January 2018, researchers finally found an underground connection. Dos Ojos and Sac Actun thus form the largest such cave system on earth.
What are cenotes?
Cenotes are doline-like limestone holes in the ground created by the collapse of caves. Unlike dolines, which are known as land sinkholes from the mountains, however, cenotes are filled with fresh water and have thus created incredible underwater worlds.
Most of the cenotes in Mexico are located in the state of Quintana Roo, like Dos Ojos, and there are about 900 of them. On the Yucatan Peninsula and across the Mexican border in Belize there are also some of these entrance holes into another world. The Cenote Ik-Kil is one of the most famous of them. In Quintana Roo alone, the total length of explored caves is close to 1,000 kilometres.
On average, the underwater caves are about 15 metres deep, but there are record holders with a depth of up to 100 metres. The Maya saw them as entrances to the underworld and used the seemingly bottomless holes in the ground as sacrificial sites. For the Maya, however, the cenotes also had a vital use for survival. Like every early advanced civilisation, they were dependent on the water supply that was guaranteed by the cenotes.
What the Nile, Euphrates or Ganges was for other cultures, this underwater world was for the Maya, which is why it is also called the "Great Maya River". Scientists also attribute the lush vegetation on the Yucatan Peninsula, despite the drought, to this hidden irrigation system. Often the only source of water during the hot dry seasons, they also attract a variety of animals to their banks time and again.
Diving in the Dos Ojos
As a diver, a visit to Dos Ojos is a truly unforgettable experience! You feel as if you are floating in 25°C warm water through the bizarre world of a stalactite cave. In the "Bat Cave" you pass bizarre stalactites or through a small opening into the fantastic-looking "Temple of Doom" with its narrow passages and magnificent rock formations.
The view is fantastic, and you get to know a variety of other inhabitants. Bog turtles, cichlids, sharpmouths, antennae catfish and various gobies and tetras feel right at home there. The Mexican cenotes are home to, among others, the blind cave tetra, which can only be found in the state of San Luis Potosí, and only in three different caves.
Caution: Diving in the cenotes can be life-threatening! Open water divers without cave experience should never descend into the cenotes without prior instruction! In case of difficulties, you cannot simply surface, but are trapped in the cave. You have to dive back the way you came, which can be up to several kilometres. Therefore, be sure to take more oxygen than you need, preferably double the amount in different tanks. Some caves are like a labyrinth, so follow the marked paths. In unexplored areas it is easy to get lost or the cave ceilings can easily collapse. Carry several torches and always remember the old diver's rule: NEVER dive alone!
If you look at the Dos Ojos cenotes from the air, you can see an almost perfect semicircular ring. Researchers believe that these fractures in the underground landscape make up the crater rim from the impact of the famous Chixculub meteorite around 65 million years ago - the meteorite that is also associated with the extinction of the dinosaurs.