the mars and venus ones are fantastic, and the venus one in particular is very science fictional in most ways. i guess you could also do a fantasy story about building a massive industrial machine to catch a VERY BIG FISH but it would be a steampunk-y fantasy not a swords & dragons fantasy
just imagine that he handwaved in a faster-than-light drive to go to a distant star system & hunt the big fish if you want
There's a place for the as-you-know-Bob type of skiffy adventure ("so there we were, sweating in our suits (specially adapted for an atmospheric pressure 92 times that of Earth and an atmosphere consisting almost entirely of CO2), when I realised that our guide had double-crossed us...")
but I have a definite soft spot for Zelazny's approach, which is effectively to say "so there we were on a hostile alien planet - was it Venus? yeah, Venus, let's go with that" and then get on with doing something more interesting.
As I recall he said that he deliberately wanted to write a mars story and a Venus story before the actual science conclusively ruled out that fun.