A suit is the best attire for any activity (even scuba diving)

As a 00, your suit is your uniform, and the British Empire was founded on a good uniform. You should wear your suit at all times for any activity, and that includes but is not limited to: skiing, scuba-diving, fist-fighting, and cavorting with members of the opposite sex. You will get bonus points for ensuring that you wear a tuxedo at all times, but a two-piece suit tailored within an inch of its life is the bare minimum.

Examples: Thunderball - Bond dons a rocket pack in the pre-credit sequence, while wearing a finely tailored suit.