UNH Ocean Seminar

Revised Depth of the Challenger Deep, the Deepest Depth on Earth

CDR Sam Greenaway
Marine Operations Lead

NOAA New Ship Construction Team

Friday, Oct. 21, 2022, 3:10pm
Chase 105

In 2020, I was asked to help independently calculate the depth of the Deep Submergence Vehicle Limiting Factor during a series of dives to the Challenger Deep. The approach my team used would be familiar to any ocean mapper: figure out vertical control, get the offsets right, model the errors, and try to squeeze out remaining error through increasingly sophisticated analysis. Along the way, we established tide datums, got confused about gravity, established benchmarks on the seafloor, dug deep into the thermodynamic properties of seawater, and eventually came up with an answer of 10,935 m. We reconcile this result against other recent efforts. Getting to the answer was satisfying enough (after all, finding out how deep the ocean is is really the heart of the whole ocean mapping enterprise), but we think advances in pressure sensors are opening up applications in ocean measurements that have been impossible up to now. 


Commander Sam Greenaway currently serves as the Marine Operations Lead on the NOAA new ship construction team. He has served in a number of assignments in NOAA, most recently as the commanding officer of the NOAA Ship Rainier. He earned a master of science in ocean engineering from the University of New Hampshire in 2010. He was commissioned in the NOAA Corps as an ensign in 2004.