Höhlensystem
Sistema Ox Bel Ha
QRSS list entry (reported by CINDAQ, 10/2024). CINDAQ's 2024 annual report gives a total confirmed length of 524 km by the end of 2024; its 2025 annual report (published 2026-03) says 'nearly 529 kilometers' in one section and 'approaching 540 kilometers' in its executive summary. QRSS lists -57.3 m with a question mark; QRSS noted in 2016 a pit surveyed to -57.3 m with explored depth beyond -61 m.
The longest surveyed underwater cave on the QRSS list (496,804 m in October 2024), running beneath the Tulum area and the northern edge of Sian Ka'an. CINDAQ, which has been resurveying it since 2018, reported about 524 km at the end of 2024.
Sistema Ox Bel Ha is a vast network of flooded passages under and around Tulum, with QRSS listing about 160 cenote entrances. It has grown both through new exploration and by absorbing caves that were once mapped separately, such as Naranjal in 2011 and Regina in 2020. Divers know parts of it by section names, notably the Naranjal-Mayan Blue area, which is used by cave training courses.
Since 2018 CINDAQ (Centro Investigador del Sistema Acuífero de Quintana Roo) has been resurveying the whole system with modern methods while continuing to push new passage. Its reports say the work started from about 245 km of older data and that more than 185 km of new passage had been found by 2025.
For most visiting cave divers Ox Bel Ha is experienced through a few well-known entrances where permanent guidelines lead into shallow, decorated tunnels with haloclines in deeper sections. Much of the system lies far from roads or on ejido land and is reached only by exploration teams with the landowners' permission.
The system is also a research archive for the aquifer, anchialine ecology and Pleistocene fauna, and CINDAQ has warned that the growth of Tulum, construction of the Tren Maya railway and the new Tulum International Airport put parts of the cave under urban development.
Geologie
Like other Quintana Roo caves, Ox Bel Ha formed by dissolution of the limestone of the Yucatán Platform along fractures and at the fresh-salt water mixing zone, and was partly dry during glacial low sea levels, when its speleothems formed.
Wasser, Strömung und Überflutung
The cave carries fresh groundwater toward the Caribbean coast above a layer of salt water; the halocline between them is deeper farther inland. QRSS lists a maximum surveyed depth of about 57 m in an in-cave pit.
Warum es wichtig ist
Ox Bel Ha heads the QRSS list of long underwater caves; in 2018 QRSS had briefly ranked Sac Actun ahead of it after the Dos Ojos connection. CINDAQ uses the system as a base for research on freshwater dynamics, anchialine ecosystems, Pleistocene fauna and the wildlife that depends on cenotes as water sources.
Bedingungen
Typical cenote water temperatures quoted by operators are about 24-26 °C. Visibility drops where the halocline or silt is disturbed.
Typische Wertebereiche aus veröffentlichten Quellen, keine aktuellen Bedingungen.
Kartierungs- und Erkundungsgeschichte
| 2007-07 | QRSS recorded the connection to Yax Chen East, giving 164.4 km and describing Ox Bel Ha as the longest underwater cave then known. [2] |
| 2011-05 | Naranjal was connected to Ox Bel Ha. [2] |
| 2018 | CINDAQ began a systematic resurvey of the system, starting from about 245 km of mapped passage. [3] |
| 2020-07 | QRSS reported Regina connected to Ox Bel Ha through a deep area between the Regina and Maya Blue sections. [2] |
| 2024-02 | QRSS reported Sistema Ni Ha connected to Ox Bel Ha and said Cenote Ni Ha had reportedly been buried under the railway right-of-way. [2] |
| 2024-12 | CINDAQ reported a total confirmed length of 524 km at the end of 2024, with just over 40 km left to resurvey. [3] |
| 2025 | CINDAQ reported 30,001 m of new exploration and 113,342 m of resurvey during 2025. [4] |
Zugänge und Tauchplätze
QRSS lists about 160 cenotes (flagged as approximate). CREER describes the system as having several hundred cenote entrances. Mayan Blue, in the Naranjal-Mayan Blue section, is a CREER-designated cave training site; many other entrances are remote or on ejido land.
Zur Orientierung, nicht zur Navigation. Hohle Punkte sind ungefähre Angaben.
Weiterführende Literatur
A short history of underwater cave exploration: dated milestones
Archaeology and palaeontology in underwater caves
Conservation, landowners and responsible access
Groundwater, haloclines and water quality in flooded caves
How underwater caves are surveyed and studied
How underwater caves form: karst, dissolution and drowned passages
Life in flooded caves: stygofauna, remipedes and the diver's footprint
Threats to underwater caves today, and how they are protected
Cave Areas of Quintana Roo (QRSS cave footprint map) ↗
Cave development on the Caribbean coast of the Yucatan Peninsula, Quintana Roo, Mexico ↗
CINDAQ (Centro Investigador del Sistema Acuífero de Quintana Roo) ↗
CINDAQ Annual Report 2024 ↗
CINDAQ Annual Report 2025 ↗
Long Underwater Caves in Quintana Roo (QRSS list) ↗
Los Cinco Cenotes: Our Year Exploring Ox Bel Ha ↗
Methane- and dissolved organic carbon-fueled microbial loop supports a tropical subterranean estuary ecosystem ↗
Quintana Roo Speleological Survey (QRSS) ↗
Review: The Yucatán Peninsula karst aquifer, Mexico ↗
U/Th dated speleothems from submerged caves in the northeastern Yucatan Peninsula ↗
Alle Angaben auf dieser Seite mit Quellennachweis (19)
| Angabe | Status | Quelle |
|---|---|---|
| QRSS lists Sistema Ox Bel Ha at 496,804 m, reported by CINDAQ in 10/2024, ranking it first among Quintana Roo underwater caves.List updated 2025-01-19. | Verifiziert | [1] |
| CINDAQ reported that Ox Bel Ha's total confirmed length reached 524 km by the end of 2024.CINDAQ 2024 annual report, published 2025-04-21. Higher than the QRSS list figure, which predates it. | Verifiziert | [3] |
| CINDAQ's 2025 annual report describes Ox Bel Ha as 'nearly 529 kilometers' long in its Ox Bel Ha section and as 'approaching 540 kilometers' of mapped passage in its executive summary.Two different figures in the same report (published 2026-03-02); no exact total was found. | Quellen widersprechen sich | [4] |
| QRSS lists a maximum depth of 57.3 m for Ox Bel Ha, marked with a question mark.QRSS 2016 update noted explored depth beyond -61 m in the same pit. | Verifiziert | [1] [5] |
| QRSS lists 160 cenotes for Ox Bel Ha, marked as uncertain; CREER describes the system as having almost 500 km of passage (as of June 2025) and several hundred cenote entrances. | Verifiziert | [1] [6] |
| In July 2007 QRSS recorded Ox Bel Ha's connection to Yax Chen East at 164.4 km, then described as the longest underwater cave in the world. | Verifiziert | [2] |
| Naranjal was connected to Ox Bel Ha in May 2011 and Regina in 2020, through a deep area between the Regina and Maya Blue sections. | Verifiziert | [2] |
| CINDAQ began resurveying Ox Bel Ha in 2018 from about 245 km of data and by the end of 2024 had added nearly 175 km of new exploration and 305 km of resurvey.The 2025 report says more than 185 km of new passage had been discovered. | Verifiziert | [3] |
| CINDAQ reported 30,001 m of exploration and 113,342 m of resurvey in 2025. | Verifiziert | [4] |
| CINDAQ thanks the Ejido José María Pino Suárez for granting access that allows its Ox Bel Ha work to continue.2024 annual report. | Verifiziert | [3] |
| CINDAQ wrote that Tulum's rapid urban expansion, the construction of the Tren Maya and the opening of Tulum International Airport make its Ox Bel Ha work more pressing, and that large parts of the system lie beneath urbanised or soon-to-be-developed areas.CINDAQ 2024 annual report, published 2025-04-21. | Verifiziert | [3] |
| QRSS reported in early 2024 that Cenote Ni Ha, newly connected to Ox Bel Ha, had reportedly been buried under the Tulum-Bacalar railway right-of-way, and that QRSS had shared survey files with UNESCO in 2023 to press for rerouting the railway.QRSS describes the burial as reported; not independently verified. | Gemeldet | [2] |
| CINDAQ is the Centro Investigador del Sistema Acuífero de Quintana Roo A.C., which facilitates research, education and conservation for Quintana Roo's cenotes and underground rivers. | Verifiziert | [8] |
| CREER training-site rules list named lines in Mayan Blue among the only places where zero-visibility and lost-line drills are permitted.Rules dated 2020-12-14 and endorsed by the listed training agencies. | Verifiziert | [7] |
| QRSS attributes Yucatán cave formation to dissolution along bedding fractures and preferential dissolution at the fresh-salt mixing zone. | Verifiziert | [9] |
| Operators describe cenote water as about 24-26 °C.Pro Dive: about 24 °C; Under the Jungle: 25-26 °C. | Quellen widersprechen sich | [10] [11] |
| CINDAQ's camera traps and acoustic monitors at Ox Bel Ha cenotes along the northern boundary of the Sian Ka'an Biosphere Reserve have recorded jaguars, spider monkeys and other wildlife using cenotes as water sources. | Verifiziert | [4] |
| QRSS described Sac Actun as the longest underwater cave, ahead of Ox Bel Ha, after the Sac Actun-Dos Ojos underwater connection recorded in May 2018; the January 2025 QRSS list ranks Ox Bel Ha first. | Verifiziert | [2] [1] |
| CREER says single-tank cavern diving is allowed only at designated cavern sites under a qualified local guide.CREER guidance dated 2025-06-20. | Verifiziert | [6] |
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