Board Thread:Warhammer 40k General Discussion/@comment-7499389-20130407223055/@comment-78.151.172.115-20140522121149

'they'll be crawling....if not Pinned to the ground' haha clearly no understanding of actual SCUBA diving/Boyles Law of gas dynamics, know all about a fictional alien race though...

If they regulate their buoyancy inside the vacuum proof armoured suit (so sure as can cope with water) and where correctly neutrally buoyant they could walk on the seabed without massive issue and fight to a degree also though they would be subject to kick back from weapons etc.

There are sources as described in the Emperors Children novel of U/W fighting as well as something on the Space Wolves page. As for actual swimming, I don’t know about that but people are saying yes.