Jellyfish in Hawaii are pretty rare to encounter. If you are ever lucky enough to swim with a large pelagic jelly then take the time to look for little commensal fish like jacks, that are using the jelly as a protective home.
There is also a rare nudibranch that is only found on man-o-war jellies. Sometimes its the little things that you have to be on the lookout for. This is why when everyone is screaming jellyfish and heading the other way I am going in for a closeup!