DEPTHX is the underwater, untethered robot that was going to explore the depths of a sinkhole in Mexico. In the first of the trial runs for NASA the bright orange DEPTHX robot was apparently lost underwater. One of the sonar sensors went bad during the robot's ascent and it was trapped under a rock overhang. The test crew was able to find the robot quickly during a scuba dive, and dislodge it. It's a good thing they gave it a bright orange shell!