check out the Kwaj dive club. you're pretty much limited to what they do as there aren't any commercial ops on Kwaj.
Ebeye might have some commercial charters as it is a much more populated island, but it exactly a tourist location.
Bikini is just a short hop away and you could dive the USS Saratoga. but I heard Air Marshall Island quit air service to up there.
EDIT: confirmed, no air service up there anymore
Bikini Dive/Tourism Information