Marine Debris Removal, Coral Sampling, and More With Navy Saturation Divers

July 31, 2024

This month, NOAA scientists and partners teamed up with U.S. Navy saturation divers to advance deep sea restoration efforts in the Gulf of Mexico—a collaboration that is the first of its kind.

Typical scuba diving is limited by the body's response to pressure. As a diver descends below the ocean surface, the surrounding pressure increases, compressing the gasses in their body. If they ascend too quickly, rapidly-expanding gasses can cause decompression sickness, also known as the bends.

a bell-shaped contraption is suspended in the air above the water's surface by cables on a large vessel — A diving bell is a rigid chamber used to transport divers from the pressurized habitat on the surface to the ocean depths, and back. Here, the diving bell is lowered into the ocean with three Navy saturation divers inside. Photo: Erin Spencer, National Marine Sanctuary Foundation

Saturation diving involves compressing divers to pressure at depth before they enter the water—staying for days or weeks in a compression chamber on the surface, then traveling to depth in a diving bell. Divers can go beyond recreational diving limits, stay at depth longer, and accomplish more work in a shorter amount of time than an expedition depending on scuba diving.

This mission, which focuses on areas in and around Flower Garden Banks National Marine Sanctuary, combines saturation diving, remotely operated vehicles, and other technologies to advance restoration of mesophotic and deep benthic communities in the Gulf of Mexico. Saturation divers from the Navy Experimental Diving Unit conducted surveys, collected biological samples, installed mooring buoys to protect the seafloor, and removed marine debris and invasive lionfish. This is one of the first significant NOAA-Navy collaborations in the Gulf of Mexico, the deepest dive by humans for a NOAA science and natural resource restoration mission, and one of only a handful of times saturation diving has been used for a NOAA mission.

This mission represents another big step forward in not only reducing threats in Flower Garden Banks National Marine Sanctuary, but also understanding and restoring mesophotic and deep benthic habitats. These areas of the seafloor that see little to no sunlight were one of many types of resources injured by the Deepwater Horizon oil spill in 2010, which released more than 134 million gallons of oil over an 87-day span. Healthy mesophotic and deep benthic communities in Flower Garden Banks National Marine Sanctuary can serve as a reference for restoration of impacted habitat.

a scuba diver holds onto a diving bell suspended by cables in the water column — A Navy Experimental Dive Unit saturation diver kneels outside of the diving bell. The bell allows them to travel from the pressurized habitat on the surface to the ocean depths. Photo: NOAA, C-Innovation, LLC

After the Deepwater Horizon oil spill, federal and state agencies formed the Deepwater Horizon Natural Resource Damage Assessment Trustee Council (DWH Trustees) to assess impacts and identify actions to restore injured habitats, species, and the services they provide. In 2019, four long-term Mesophotic and Deep Benthic Community projects were approved to focus on habitat assessment, seafloor mapping, deep-sea coral propagation, and active management and protection of benthic habitats. Saturation diving has now joined the list of the many methods used to advance these critical projects.