The Deep Phreatic Thermal Explorer (DEPTHX) is an autonomous underwater vehicle designed and built by Stone Aerospace, an aerospace engineering firm based in Austin, Texas. It was designed to autonomously explore and map underwater sinkholes in northern Mexico, as well as collect water and wall core samples. The DEPTHX vehicle was the first of three vehicles to be built by Stone Aerospace which were funded by NASA with the goal of developing technology that can explore the oceans of Jupiter's moon Europa to look for extraterrestrial life.

Depthx är en undervattensrobot utvecklad av NASA. Roboten är tänkt som ett utvecklingsprojekt inför planerade utforskningsresor till en av Jupiters månar med namnet Europa.