We began our 45-minute walk through the jungle, encountering three stream crossings ranging from chest to ankle deep. In a clearing before the cave entrance, we took a final bathroom and water break before stashing our water bottles. Our guide outlined our journey through the cave, and explained to us how important it is for us as visitors to minimize our impact on the cave environment. ATM Cave sees many tour groups each day, especially during peak season, and the cave environment is fragile. It was recommended to wear long sleeves instead of sunscreen and bug spray, as these chemicals would immediately wash off as soon as we began swimming. We were also instructed to be careful of our hand and foot placements, as oils from our skin can damage the rock crystal formation, and visitors must take extreme care when walking among the Mayan artifacts.
While ATM Cave is a popular place, our guide timed our entrance into the cave to give our group space and create a feeling of solitude. Though I knew there were groups ahead of and behind us, it felt like we were the only ones there for most of the tour.
Entering the cave was our first commitment to the adventure. We pushed off from boulders on the edge of the stream, and swam across a deep, turquoise colored pool of water to reach a limestone ledge. There, we turned on our lights for the first time, and descended into the darkness of the cave. The route consisted of walking through a shallow stream, portions of wet limestone, and deeper pools that required a short swim. My headlight beam illuminated huge ceilings hanging above us, covered with folded and rippling speleothem clusters, glittering calcite crystals, lumpy pillars and towers of stalagmites. We moved through the pools and shallower creek beds, over sharp and smooth limestone with polished corners, worn down by the flow of water, and walked over river pebbles. We caught glimpses of bats flying above, and even spotted one clinging to the limestone wall, and a few fish and small crustaceans could be seen in the water.