Shore diving at CDM is pretty easy, and not too bad. A few years ago they added to it by placing some coral/fish structures. They look like swiss cheese half domes and are straight out from the dock and a little bit north. You will be able to rent tanks and weights there, either from Del Mar Aquatics which has moved but is still close, from the dive concierge on the Casa del Mar dock, or from Scuba Shack, just south of the Atlantis Submarine shop. Tanks and weights were $6 high season before last. You can get in the water down steps on the CDM "beach", off the CDM dock via giant stride, just north of Tikila which is connected to the old Del Mar Aquatics building, or at Scuba Shack if you get tanks from them.Casa del Mar is not right on the ocean, but across the street. It's easy to cross on street level by going through the restaurant, or you can use the walkway that goes over the street. Casa del Mar has lockers that you can use in the old Del Mar Aquatics building. Bring your own paddle lock. I suspect that the CDM dive concierge is now located in that space. I've stayed there many times, but wasn't there last year, so the Del Mar Aquatics change is something I'm not familiar with.If you stay at CDM and dive, be sure to upgrade to a balcony room. (Or patio room if you're on the ground floor. Djdiverdan on this board knows the official name of that type of room. It's not the lowest level room anyhow.) Actually, I'd do that even if I wasn't diving as the standard rooms are very small.I've done both day and night dives. You need a surface marker/buoy during the day. There is some boat traffic, but it's not horrible. Just pay attention to it. The current generally goes from south to north, so plan your dive accordingly, but I've gone the "wrong" direction on dives and fighting the current on the second half of the dive wasn't horrible. I think the shops around there open pretty early, like 7am, and I'm not sure when they close, so inquire when you rent your tanks and weights. Max depth will be about 25 to 30 feet off "the ledge", which you can follow on your dive.