Fitness requirement for Divers is higher than the standard RN requirements.
Diver Physical Fitness Test is 1.5 mile run as a squad in 15 minutes, followed immediately after by another 1.5 mile run individual best effort...you need to get in under 10m 30s. There then follows sit-ups (40 in 1 minute), dips (I think 12 needed) and pull-ups (again 12 I think) - these are aproximate as I think the requirement has changed slightly since I did the test.
bythesea is right in that basic fitness requirement for RNR basic training as stated in his/her post
Dressing up in rubber and hurling yourself into a wet, weightless environment with things attached to ´umbilicals´...Freud would have a field day.