Deep-sea diving experts working for the British Royal Navy recently helped submarine historians solve a century-old U-boat mystery, drawing on their past military experience and teamwork to do so.

They say the best way to take up a new hobby is to jump in the deep end, and a group of divers in north Queensland has done just that — delving 16 metres below the waves to draw under water.

This experience alerted the navy to the problem of breathing normal air during a deep sea dive, and it started experimenting with a helium-oxygen mix. A US naval diver preparing for a dive in 1955.

Then-Spc. 5 Andrea Motley Crabtree in the Mark V deep sea dive suit at Fort Rucker, Ala., 1985. (Courtesy of retired Master Sgt. Andrea Motley Crabtree) Retired Army Master Sgt. Andrea Motley ...