The MBARI Mapping AUV is a torpedo-shaped vehicle equipped with four mapping sonars that operate simultaneously during a mission. The sonars are a swath multibeam sonar, two frequencies of sidescan sonars, and a sub-bottom profiler. The multibeam sonar produces high-resolution bathymetry (analogous to topography on land), the sidescan sonars produce imagery based on the intensity of the sound energy's reflections, and the subbottom profiler penetrates sediments on the seafloor, allowing the detection of layers within the sediments, faults, and depth to the basement rock. The vehicle is launched on programmed missions and runs on its own battery power until it returns to the ship, as programmed, for recovery.
Such robots are great for such underwater explorations. Compared to a human being, they have better underwater capabilities- they last longer underwater, have increased depth explorations and also have better detection mechanisms. The main thing is still safety when such robots are concerned, as using such robots reduces the chance of a fatal accident happening to zero.
Also, I believe that such AUV robots will have great potential uses, for example, the study of hurricanes, coastal erosion, ocean exploration and fisheries stock assessments. As a student who is particularly interested in defence technology, I also believe that such robots will be able to employ anti-mine technology and also improved submarine detection. Current technology has already acquired some of the above "skills", but such "skills" are not perfected as the robots will still make errors like a human. Thus, much work is still needed on robot recognition so that differentiation between background and the surrounding objects can be done without errors. There is so much that can be done to improve AUVs, but due to the limitations of present technology, the problem still exists such that the "skills" of the AUVs are limited too.
There is also a Singapore Robotic Games competition which involves underwater robots: http://guppy.mpe.nus.edu.sg/srg/urc.pdf . Such competitions promote the research in such categories of underwater exploration and thus will be able to spark potential engineers to create even better AUVs.