CUSS I was a converted Navy barge used in Project Mohole, an early effort at deep undersea drilling. Mohole was a National Science Foundation research project, intended to drill down to the Mohorovicic Discontinuity, the boundary between the earth's crust and the mantle. Starting in 1961, CUSS I drilled off the coast of California in 11,700 feet of water. Mohole was cancelled in 1966 due to the cost of the project.

Correct answers were received from: Kevin J. Foster, Jeff Arban, Michael Flora, John Eastlund, Bob Harmer, Ron Grout, Bill Marshall, Wendell Boggs, Gary Landrum, James E. Smith, Norman Heath, David Lednicer.