Actun Tunichil Muknal

usually abbreviated to "ATM"

A Mayan sacrificial burial site near San Ignacio. The site is contained entirely within a cave system, and access to the relics is gained via some 500 m of climbing over rocks, wading and swimming through water that is at times over 1.5 m deep. The cave was a sacred site for the Mayans and it contains many examples of pottery, ceramics, and stoneware, as well as several sets of human sacrificial remains, one of which (known as the "Crystal Maiden") has been almost entirely covered in limestone crystals by the water in the cave. The site is a 45-minute drive from San Ignacio, and, due to the caving aspect, it may only be visited when accompanied by an official guide (who will provide appropriate safety equipment) and you can't take photos inside. Most tour companies in San Ignacio are able to offer officially guided tours.