DEPTHX, 2006: DEPTHX is a hovering autonomous underwater vehicle that explored flooded cenotes in Mexico. The cenotes of Sistema Zacat´on in Tamaulipas, Mexico, are flooded sinkholes, exotic geological formations with unique water chemistry. The deepest, Zacat´on, is over 300m deep. None of the cenotes were mapped before this project. The goals of the DEPTHX project were to construct metrically accurate three-dimensional maps of the cenotes, and to collect environmental data, imagery, water samples, and core samples.