Known Length of the Deepest Cave in the Western Hemisphere Surpasses 100 Kilometers

The PESH Expedition survey of Sistema Huautla added length to the already record-breaking cave as well as preparing for more explorations in 2024.

HUAUTLA DE JIMENEZ, Mexico, June 6, 2023 /PRNewswire/ — Cave explorers from around the world hit a milestone during their exploration and survey of the deepest cave in the Western Hemisphere, Sistema Huautla, this Spring. The international team of 37 cavers and support staff added 222 meters to the known length of the cave system during the most recent Proyecto Espeleologico Sistema Huautla, or PESH expedition. The known length of Sistema Huautla is now just over 100 kilometers or 62.27 miles. Teams also added three kilometers to the Cueva Elysium, a nearby but currently unconnected cave system. The accomplishments were announced as part of the celebration of International Cave Week, June 4-10.

In addition to continued exploration and surveying, the April 2023 PESH Expedition had several objectives including rigging 2,000 feet of rope in two other nearby caves. Both caves are far deeper than any cave in the United States. The rigging in these caves were left in place (although the ropes were pulled to prevent damage from seasonally rising waters) for next year’s expedition. The 2024 expedition will focus on these other two caves for exploration and surveying, which will enable the team to add these caves to the overall cavern system.

Discovered by Texas cavers in the 1960s, the caves in Huautla de Jimenex, Oaxaca, Mexico, have been the center of annual expeditions starting in 2014. PESH co-leaders and renowned cavers, Tommy Shifflett from Virginia and Bill Steele from Texas, have planned the April expeditions from the start.

“We plan the expeditions in April because it’s the driest month of the year in the mountains,” said Steele. “With teams camping deep underground with no way to contact the surface, we are always keeping an eye on water levels. This April it was wetter than normal; that hampered our exploration somewhat.”

PESH expeditions are made possible by sponsorships of various organizations, and this year the foundation of the largest cavern in Texas, Natural Bridge Caverns, joined the effort. Natural Bridge Caverns is considered Texas’ most actively explored cavern system, an effort Steele has participated in with co-owners Brad and Travis Wuest.

“We were pleased to both support PESH and to journey to Huautla ourselves,” said Brad Wuest. “Discovery is at the heart of our work here at Natural Bridge Caverns and we appreciate the efforts of cavers around the world to further explore and understand these incredible natural wonders.”

The current surveyed depth of Sistema Huautla is 5,118 feet, equivalent to four Empire State buildings. Cave geologists estimate the vast natural underground labyrinth is as old as 15 million years. All data collected is shared with Mexican cave scientists including information on cave adapted lifeforms, paleontological remains of extinct animals (which are photographed but left in the cave), and ancient climate patterns through analysis of stalagmites. The 2023 expedition also achieved another significant milestone – it carried the flag of The Explorers Club, an award granted to the top expeditions in the world. With the system now over 100 kilometers, excitement for further exploration continues to grow.

“We are grateful to the people of Huautla and the international community of cavers who continue to encourage us to keep exploring,” said Steele. “It’s one of the most magnificent caves in the world and it’s a privilege to uncover more of its beauty and wonders.”

For photos and maps, visit

About PESH: PESH Expedition is a 501(c)3 non-profit created to support the exploration, survey, and comprehensive speoleological study of the Sistema Huautla area caves. Annual expeditions have been underway since 2014, and the results of each expedition supports the ongoing underground research of Mexican scientists. For more information about the PESH Expedition as well as updates on plans for 2024, visit

About the Natural Bridge Caverns Heidemann – Wuest Foundation: Established by Natural Bridge Caverns founder Clara Wuest Heidemann in 1997, Heidemann – Wuest Foundation (HWF) supports not-for-profit charities that focus on youth and agriculture, education, heritage, faith, wildlife, conservation, exploration, law enforcement, and veterans. Each year the HWF contributes more than $100,000 to charitable organizations in the San Antonio and New Braunfels area. For more information on the philanthropic work of both the HWF and Natural Bridge Caverns, visit

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SOURCE PESH Expedition