A decommissioned World War II-era destroyer docked near downtown Buffalo in New York is taking on water and listing...
Swimming Underwater - Military Tests
NEVER SWIM ALONE - ESPECIALLY UNDERWATER DRILLS
This is a technique video on swimming about 40m underwater in the pool. It is ALL technique. Sure having the ability to hold your breath is good but you will ace the test with proper technique.
Big arm pulls, good hard kicks with streamlined arm recoveries - repeat. Try to get 25m in 4-5 strokes. Anymore is a waste of energy and could be the reason why you cannot get past 25m.
See more on training besides just swimming:
Run, PT, lift, ruck, swim to prepare for any fitness test and any military, police, fire fighter training / selection program.