Colour, although rather dim.
Last night's one, before I forget, was about a recently salavaged MkII-D U-boat whose crew who mutated into territorial crocodile-esque creatures out of a desire to leave their isolated world, I suppose after losing their way in the Arctic Circle. The sub was found by an Italian trawler in the Atlantic after its front end had surfaced somehow and the thing had drifted a long way facing vertically.
Well, that's what you get when you mix an old film with a few newer documentaries.