U.S. Marines with Charlie Company, 2d Reconnaissance Battalion, 2d Marine Division set up 360 security during a dive mission in Key West, FL, Jan. 24, 2018. The Marines executed various training exercises such as stealth insertion, to sub-surface swimming objectives as part of their combat readiness evaluation in preparation for an upcoming deployment.

U.S. Marines Corps photo by Lance Cpl. Brennon A. Taylor

Watch Recon Marines conduct dive training in the video below:

https://www.youtube.com/watch?v=tA-jGOfnoHU