You don't need numbers, just a chart and compass which usually comes with the boat. Carysfort is off of North Key Largo and most of the boat rentals are farther south. Our usual routine is to make the long run to Carysfort first and spend most of the morning there. Morning is usually the calmest and best time of day for snorkeling. Then, work south along the outer reefs to the Elbow, French, and ending up at Molasses. That puts us in position for a short run back to the dock. We usually stay with the outer reefs because they are closest to the Gulf Stream and the visibility is usually best at these reefs. If a chop builds up later in the day,or if there are strong currents on the outer reefs (not typical, but it does happen) there are good reefs close inshore that stay calm like the Dry Rocks, the Christ Statute or the Horseshoe and these can be an alternate if a breeze kicks up in the afternoon. Thus route will put you in position for a short run back to the rental place at the end of the day. Believe me, any 3 or 4 of these reefs will more than fill up your day!
Sounds like you plan on solo diving. Although the keys shallow reefs are solo-diveable (personally I do not solo dive), they are different from what you are used to. The surface is close but not "instantly available" like in extreme shallow diving. They are deeper (15 to 35') and do have corals and things that can snag gear, and they also have interesting arches and swim-throughs and ledges that you can find neat things underneath if you want to explore, but where you might not want to venture solo. I would at least think about diving with a buddy in this area, especally if it is your first time here. It might allow you to more comfortably enjoy the reef. There will certainly be plenty of people on your CR trips, but if your snorkelling friends are not capable of freediving to assist you in the (remote) chance you would need it, you might want to find a buddy for your boat rental day.
