I'm working on my Masters Degree in the Robotic Systems Laboratory at Santa Clara University. RSL does a lot of in-the-field robotics research and I recently got to go on a deployment to test the lab's 150lb ROV called Triton. We went to a fairly shallow man-made water way in Foster City, CA to verify that Triton was working properly and to test an acoustical positioning system that will be used for a cluster ROV project we're developing. The water was very murky so we couldn't see much through the video feed, but it was fun to joystick Triton around anyway. I learned a lot about this class of ROVs during the trip, and have definitely come up with some new design features for my smaller ROV based on the experience. Here are some photos (more to come, but I have to find the memory card that was in my other camera)...
Wheeling Triton out to the truck
Laying out the 200' tether. It's fairly stiff due to the amount of buoyancy and insulation it has. Also, it can't be bent to less then about a 2ft radius or the wires inside may fail.
Attaching tether to Control Box. Look at all the equipment needed to run this thing!
Triton in front of control box with tether in background
Triton in the water
Driving Triton through the video feed (Triton visible in background)