I didn't see any bigger tanks. But I wasn't really looking for one. They do have Nitrox:
Roatan Dive Shop | Honduras Scuba Diving Rentals | Anthony's Key
Cocoview also has a day program for cruise divers.
Welcome to CoCo View FAQ The Prince Albert wreck is just offshore.
AKR has the dolphins - it's an easy 60' dive. Extra charge though - I think it's about $130 now.
CCV is probably about the same distance away from the cruise port in Coxen Hole as AKR, so it's a choice of North side vs. South side diving. Bigger stuff is found on the north typically. No one will pick you up at the cruise port besides AKR but finding a cab won't be a problem...lol. Negotiate the fare in advance - I've heard prices double when your ship docks.
We dove with Coconut Tree Divers in the West End and had some cruise divers join us once or twice. It's a longer cab ride but you could do tourist stuff in the West End afterwards time permitting. At AKR or CCV you're kind of stuck there. The closest non-resort stuff from AKR
is the West End - 10min cab ride - and French Harbor is a little far to walk to from CCV.
Coconut Tree Divers will probably watch your gear while you look around if asked - we left ours there all week. There's at least a dozen places to eat/drink within 1/4 mi. either way also. Their morning boat leaves at 9AM - I couldn't begin to guess how long it takes to get through traffic in Coxen Hole when your ship is there though - but IIRC all the cruise divers did the afternoon dives with us. They have 2 single dives - 1PM and 2:30, the boat returns between dives. The 2:30 dive was back to the dock around 4PM - they do shallower sites closer offshore. They have Nitrox and Steel 100's - but call them first as I think they borrow them from someone else. Also, they did it for us as my group (7) was most of their business all week - it may be different on a one-day rental.