Note: A ROV is essentially a remote-controlled underwater robot
"On Friday September 3, 2010 the St. Louis County Minnesota Volunteer Rescue Squad was called in to assist the City of Virginia, Minnesota Police Department in locating a stolen Caterpillar D9 track-type bulldozer tractor.
The City of Virginia Police Department observed an oil slick on the water surface of a mine pit along with disturbed brush leading down to the water some 300 feet below ground level. Concerned that the driver may have been trapped in the equipment, they requested assistance from the St. Louis County Sheriff Volunteer Rescue Squad to investigate slick with their underwater experience and technology. This could have been done by divers except it would have been next to impossible to transport heavy dive gear down the steep cliff.
After arriving at the mine pit and evaluating the scene, SLC Volunteer Rescue Squad Captain Tom Crossmon called in his High Level Team to transport the ROV and its tether down the steep rocky face to the water surface. Because the ROV only weighs 10 pounds, team members were able to rig the VideoRay submersible and tether to their bodies while belaying down the face....
....Crossmon operated the....ROV from the squad's mobile command vehicle...., located the oil slick on the surface, submerged and then positively identified the Caterpillar D9 within minutes at a depth of 20 feet. The rescue squad performed a pattern search around the machine for any sign of the driver and did not find anything...."
For more information, see: http://www.rovworld.com/article4771.html