Years ago, I saw an old black and white horror film on television late one night. It had people crossing a "living" swamp which was made of these odd fungus-like creatures that covered the surface of it. The people could walk across the swamp by wearing snow shoes, but I remember one man got pulled in by the creatures. I think there was lots of fog/mist around the swamp as well. Anybody know what the film was?

The Lost Continent

Thank you, Quinn! It was indeed The Lost Continent (I just watched it on Google Videos). It was the late 1970s when I saw it on television but I must have watched it on a black & white set and therefore remembered it as a B&W film (it was actually made in 1968 and in colour).

You're welcome.