Deep beneath the surface of the Yucatán Peninsula, a submerged archaeological site has yielded an astonishing collection of 19th-century weaponry. Archaeologists from Mexico’s National Institute of Anthropology and History (INAH) have been documenting a vast array of artifacts hidden within the Síis Já cenote, located under the Ex Convento de San Bernardino de Siena in Sisal, Valladolid. This remarkable discovery sheds new light on the tumultuous period known as the Caste War of Yucatán (1847–1901), revealing a unique underwater context where government forces likely disposed of their arsenals to keep them out of the hands of Maya rebels.
The Síis Já cenote, whose name translates to "well of cold water" in the Mayan language, serves as a natural time capsule. During a recent intervention aimed at assessing the site's condition following reports of unauthorized access, specialists from INAH's Subdirectorate of Underwater Archaeology (SAS) recorded more than 150 firearms resting on the cenote floor.
Convent of San Bernardino de Siena, en Sisal, Valladolid. (G. García, SAS./INAH)
An Arsenal Hidden in the Depths
Among the submerged artifacts, researchers have identified Spanish and English rifles and muskets, alongside a remarkably preserved iron cannon still mounted on its original wooden carriage. The sheer volume of weaponry suggests a deliberate and hasty disposal by the Yucatecan government army between 1847 and 1848, a critical early phase of the Caste War, also known as the Maya Social War.
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"The work of INAH is not only to recover objects or zones, it is also to preserve historical narratives, guaranteeing that the sites continue to be a source of identity, learning, and cultural continuity for present and future generations," stated Claudia Curiel de Icaza, Mexico's Secretary of Culture, emphasizing the importance of protecting the nation's heritage.
A rifle from the Caste War in the cenote. (G. García, SAS/INAH)
Beyond Weapons: A Tapestry of Artifacts
The cenote's depths hold more than just the remnants of war. Scattered among the firearms are diverse objects spanning centuries of history, from the pre-Hispanic era to the 20th century. Archaeologists have documented ceramic vessels, incense burners, majolica, Talavera pottery, and porcelain. These artifacts remain in situ to favor their conservation in the stable underwater environment.
To study the findings without disturbing them, underwater archaeologist Gustavo García conducted a detailed photogrammetric survey. By capturing multiple images of a rifle, the cannon, and concentrations of materials, the team is creating highly accurate three-dimensional models. This advanced 3D registration allows experts to analyze the archaeological evidence from various angles, contextualize the discoveries within their original setting, and reconstruct historical practices associated with the site.
Researcher recording the artifacts found in cenote Síis Há, en Yucatán. (G. García, SAS/INAH)
Protecting a Fragile Underwater Heritage
Despite the historical significance of the Síis Já cenote, the site faces significant threats. The recent INAH expedition noted the presence of collapsed illegal infrastructure, including stairs and bridges, which have directly impacted the cenote and its delicate ecosystem. Furthermore, the discovery of unauthorized "lifelines" indicates that recreational divers have intruded upon this protected area.
Environmental changes are also a cause for concern. The total absence of typical catfish, known locally as ahlu, suggests potential contamination of the aquifer. In response to these critical conditions, INAH and the Fundación Convento Sisal Valladolid A.C. have issued an urgent appeal to the community to help protect the site.
Plans are underway to resume comprehensive research, beginning with the careful removal of modern debris and a systematic survey of the underwater landscape. As these efforts continue, materials previously recovered from the cenote in 2003 will soon be returned to the Ex Convento de San Bernardino de Siena to be exhibited, ensuring that the legacy of the Caste War and the secrets of Síis Já are preserved for all to see.
Top image: View of the Síis Já cenote, where archaeologists are documenting artifacts from the Caste War. Source: G. García, SAS / INAH
By Gary Manners
References
INAH. 2026. El INAH continúa con registro de vestigios encontrados en el Cenote Síis Já, en Yucatán. Available at: https://www.inah.gob.mx/boletines/el-inah-continua-con-registro-de-vestigios-encontrados-en-el-cenote-siis-ja-en-yucatan
Milligan, M. 2026. Caste War weapons found in Yucatán cenote. Available at: https://www.heritagedaily.com/2026/04/caste-war-weapons-found-in-yucatan-cenote/157825
