In 1939 the Sargo-class submarine USS Squalus (SS-192) sank off
the coast of New Hampshire during a test dive. On May 23, the
diesel-electric submarine went down resulting in the death of 26
sailors. Thirty-three survived.
https://www.navalhistory.org/2014/05/23/remembering-the-uss-squalus-75-years-later