OK... redundant is solo... it can be cave as well... Get to the back of that "cave" and let your first stage bomb on you and then tell me how you don't need a redundant air supply. Already said you don't have to take a cave class to dive in caves, but you do have to follow the rules of cave diving (oddly enough one is dont dive beyond your training). I don't know about dive boats in California, but in Florida if it is a deep dive you don't get to go without a card that says you are either an Advanced diver or Deep diver. Most specialties are for people that WANT someone to show them how to complete a specific type of dive... Thats not you but the reality is boat owner won't take your lack of a c-card on as a liability when running trips.... It's coming to the point that if you are not a CERTIFIED PSD/Blackwater diver you wont be doing that either... too many PSD divers dying because they didn't have the training/re-training that goes with the job.
now I'm done.