Archaeologists are rushing to find what they can, as the building of the Maya Train system threatens cenotes and other submerged ecosystems. Sunken temples such as Taposiris Magna and artifacts from ancient coastal civilizations have shown that plenty of history has instead been submerged. And when cave diving along the coast of Mexico’s Yucatán Peninsula, archaeologist Octavio del Río and professional cave diver Peter Broger discovered human remains that had not seen dry land since the last Ice Age. Between the resort towns of Tulum and Playa del Carman, what tourists usually don’t see is the thousands of freshwater sinkhole caves known as cenotes. The oldest known skeleton to surface among the cenotes is known as Eva de Naharon, or Eve of Naharon—at 13,721 years old, she’s the oldest known human fossil in the Americas so far.