Autonomous underwater vehicles (AUV) are untethered submarine robots that can be used to carry out deepwater mapping and seabed-characterization surveys (seafloor to 150-m depth). AUV surveys are used in the marine petroleum industry for various exploration, environmental, geohazard, and engineering applications. Typically, AUVs are launched from a mother ship. They execute a preprogrammed survey pattern and are recovered, and the survey data are downloaded for analysis. Data on water depth, geomorphology, stratigraphy, and structure ranging downward to 150 m below the seafloor routinely are collected using a variety of sensing technology. Principal survey tools include a multibeam echo sounder to provide water column, bathymetric, and seafloor-reflectivity data; a side-scan sonar to provide high-resolution seafloor imagery; and a subbottom profiler (1-to 24-kHz seismic-reflection tool) to show subseafloor stratigraphy and structural features. Other AUV survey tools can include still cameras, lidar scanners, magnetometers, geochemical sensors (CO 2 , CH 4 , PAH, dissolved oxygen), and temperature and salinity sensors. AUV surveys help deepwater exploration and development to proceed efficiently and safely and thus have become an indispensable tool for deepwater operations.