Difficult call on the Frogmen. WW2 style frogmen seem to be non-existent at the moment; I do vaguely recall one of them years ago (maybe in the RAFM range?), but I honestly can't remember details. I do know they're pretty much not available at the moment, unless the gentlemen who discussed making a range of divers here has made any progress in his quest.
Hardsuits are a little easier to come by...
There are some good "Hard Suit" diver types available from Brigade, and Recreational Conflict does them in a style similar to that of "Bioshock"; there is also a single hard suit diver in the queue for release with the Reaper "Chronoscope" Range; I like the fig, though he's fairly static (actually sort of an appropriate pose given the weight he's wearing).
Scheltrum also do some excellent diving suit types in a variety of styles, and HLBS did them at one time, although I'm not sure whether they're still available.
Brigade does a nice Hardsuit set. I believe one of them is the crew on the surface of the water. Can't recall off hand if the diver comes with them or is separate (probably comes with them).
Finally, Reverisco does some great "20,000 Leagues" style hardsuits, ala Disney, with removable helmets. However, these are very slimly proportioned figs, and I have been warned that they don't even scale up with "true 28" size figures like Pulp, etc.
-Doc