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Sistema Huautla

Descent into Sistema Huautla
Descent into Sistema Huautla. / Kasia Biernacka, Wikimedia Commons / CC BY-SA 4.0

WorldBlue  In short

The deepest known cave in the Americas, in the Western Hemisphere, is Sistema Huautla. The known depth of the cave is 1560 m, length of its passages – 100 114 m.

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GPS coordinates
18.1212 N 96.8 W
Location, address
North America, Mexico, Oaxaca, Huautla de Jimenez municipality, south from San Andrés Hidalgo. Coordinates show the entrance in Sótano de San Agustin
Alternate names, parts of the cave system
Sótano de San Agustín (one of the best known entrances), Cueva de la Peña Colorada (southern part) and many other names of separate parts of the cave
100,114 m
1,560 m

Map of the site

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WorldYellow In detail

Scheme of Sistema Huautla in 1994
Scheme of Sistema Huautla in 1994. / Steve Jurvetson, Flickr / CC BY 2.0


Sistema Huautla is one of the best-known caves among cave explorers, especially Americans. It belongs to the most spectacular caves in the world. The landscape in the cave is quite diverse – there are amazing and very large cave formations, giant cave rooms, waterfalls, lucid lakes, and sumps.

Sistema Huautla has developed in Sierra Mazateca Mountains, in Cretaceous (mainly – Middle Creataceous) limestones through karst processes. Part of the cave system is protected by overthrusted Jurassic flysch – a sequence of sandstone and shale that does not dissolve in water. This is an unusual case where older rocks cover younger ones.

This area receives much rain and, as a result, there have developed many extensive cave systems.

The known length of cave passages is 100 114 m (26th in the world) and the depth is 1560 m (11th in the world) (figures for July 2022). The cave system has 29 known entrances.

Sistema Huautla, descend into abyss
Sistema Huautla, descend into abyss. / Kasia Biernacka, Wikimedia Commons / CC BY-SA 4.0

The cave depth is measured from the highest point in the cave system (Nita Nanta entrance) to the lowest point – the maximum reached depth in Sump 9 (nicknamed also “The Mother of All Sumps”).

The main entrance is Sótano de San Agustín – this part, if measured separately, is 859 m deep.

Sistema Huautla is a dangerous cave and its research requires a very high level of skills and diverse equipment. Especially complex are the numerous sumps that require very risky cave dives. Occasional rain somewhere in the mountains may bring sudden flash floods. Expeditions should bring through these sumps all their belongings because crossing the numerous sumps takes weeks and even months, all the time bearing in mind that flood can come any minute.

This giant cave has a rich cave fauna – there are known 35 species, including at least one new species for the science – a tarantula spider Hemirrhagus billsteelei.


Sistema Huautla, lake in the cave
Sistema Huautla, lake in the cave. / Kasia Biernacka, Wikimedia Commons / CC BY-SA 4.0

The entrances in the caves almost certainly were known to locals – Mazatec people. In their culture caves were important for religious ceremonies and also – burial, although there is no information on whether any part of Sistema Huauatla contains such archaeological values.

Cave researchers discovered the entrances in Sistema Huauatla in 1965, during the expedition of cavers from Austin, Texas. They discovered several cave entrances that were fairly close together and it was assumed that these all belong to a single cave system.

In 1977 the depth of 1 325 m in the San Agustin sump was reached. Several times (in 1979 and in 1981) expeditions tried to dive through this sump.

In 1984 the giant southern part of the cave – Cueva de la Peña Colorada – was explored by the legendary US speleologist Bill Stone.

Impressive cave critter in Sistema Huautla
Impressive cave critter in Sistema Huautla. / Kasia Biernacka, Wikimedia Commons / CC BY-SA 4.0

Especially complex and dramatic expedition took place in 1994, also led by Bill Stone. It could be one of the largest cave exploration expeditions ever: it lasted 135 days and involved 44 people.

There was used a specific technology: a rebreather. This technology was developed especially for the exploration of Sistema Huautla and it can recycle the breathed air, in order to dive through large flooded sections – sumps.

The expedition reached Sump 9 – an extremely complicated sump that was dived for 440 m in length and 81 m in depth. It led towards the only exit of the cave stream – the spring of Peña Colorada some 10 km south of the San Agustin entrance, but this connection was not dived through and more than four kilometers of unexplored cave system were in between.

Another large expedition with 40 participants was organized in 2013. Over a two month period, they reached the depth of 1 545 m and the total length of cave passages reached 64.2 km.

A large-scale long-term research project – Proyecto Espeleológico Sistema Huautla (PESH) – was started in 2014 with yearly expeditions in the cave system.

It is expected that further research will make the cave longer and, possibly, also deeper.


  1. Sistema Huautla Proyecto Espelologico. Contains a large set of diverse maps. Accessed in 2 April 2022.
  2. Cueva de la Peña Colorada, Beyond the Sump. Accessed in 2 April 2022.
  3. Maps of Cueva de la Peña Colorada, Beyond the Sump. Accessed in 2 April 2022.
  4. Andreas Klocker, Cueva de la Peña Colorada, Sidetracked Magazine. Accessed in 2 April 2022.
  5. James H. Smith, Jr. Hydrogeology of the Sistema Huautla Karst Groundwater basin (PDF file), Association for Mexican Cave Studies (AMCS) Bulletin No 9., 2002. Accessed in 2 April 2022.

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