INDIAN OCEAN (April 14, 2014) Operators aboard the Australian navy vessel ADF Ocean Shield move U.S. Navy's Bluefin-21 into position for deployment. Using side scan sonar, Bluefin will descend to a depth of between 4,000 and 4,500 meters, approximately 35 meters above the ocean floor to spend up to 16 hours at this depth collecting data. Joint Task Force 658 is supporting Operation Southern Indian Ocean, searching for the missing Malaysia Airlines Flight 370. (U.S. Navy photo by Mass Communication Specialist 1st Class Peter D. Blair/Released)
4,500 meters is almost 3 miles deep. That won't get you to the very deepest part of the ocean, which is more like 7 miles, but it's pretty darn deep, and still deeper than most conventional submarines.
Bluefin is now owned by Batelle, a not-for-profit research outfit headquartered in Columbus, Ohio, where I lived when I was in Junior High School. There is a similar outfit in San Antonio, Texas, which is just down the road from Austin, called the Southwest Research Institute. They are called non-profits now, but when I first ran into them they were called not-for-profit. I took this to mean that they could make money from what they were doing, but it was all plowed back into their organization or research, not distributed to stock holders, because there aren't any stock holders.