Frogman!. J.E. Macdonnell's Royal Australian Navy World War II Fiction, #11

Petty Officer Clive Gellatly was a former boxer who had been in the Royal Australian Navy for about ten years. But he was champing at the bit for more athletic duty. So when a request came through to join a suicide squad of frogmen, he was quick to sign up. He was taken to a remote oceanside base where he trained with another four men for several months .and along the way the five of them coalesced into a strong, capable fighting unit.
Then came their first big mission-to destroy a powerful radar station smack in the middle of a Japanese-held island!