Special thanks to the always amazing Popular Science for this!
The U.S. Naval Construction Battalions (aka: the Seabees) build all sorts of military constructions projects for the U.S. Navy.
*Fun Fact*
Detroit’s Selfridge has one of the best Seabees units in the U.S. Naval Reserve!
Naval Mobile Construction Battalion 26, based at Selfridge Air National Guard Base, was awarded the Rear Adm. John R. Perry Award as the most outstanding naval construction battalion in the U.S. Navy Reserve.
From salvaging wrecks to building aquatic infrastructure, master divers like Chief Warrant Officer James Emerson handle some of the U.S. Navy’s most complex subaqueous projects—because if something is tricky on dry land, it can be diabolical in the drink.
Emerson is in charge of turning Seabees (the name comes from the abbreviation for “Construction Battalion”) into underwater experts. Out of 160 Seabee divers, only 2 to 4 percent will ultimately earn the title of “master.”
Seabees
http://www.public.navy.mil/seabee/Pages/default.aspx
Learn more
https://www.navy.com/careers/engineering-applied-science/construction#ft-key-responsibilities