Board Thread:Warhammer 40k General Discussion/@comment-7499389-20130407223055/@comment-6078851-20130408022527

that's not actually that dumb a question, for 2 reasons - both logical i hasten to add :)

1) space marines are primarily infantry - mobile land based troops. being land based troops negates the need for swimming.

2) power armour is a self contained, full on proper environment suit. again this negates the need for swimming.

now, can they actually swim? i would say yes simply because they are soldiers trained in everything, but they don't really have any need to be able to swim so maybe they can't.