There is no shore diving at Ramons... however, you can snorkel off the end of the dock any time and there are quite a few things to see. Grunts and small school fish hide under the pier, and we saw rays pass through multiple times. There are some old anchors and such to find. Tarpon commonly patrol the dock at night, probably because it's lit up with blue lights along its length. The swim deck is just past where the grass bottom turns to sand.
We had our own fins, masks and lights with us, so we just hopped in whenever we wanted, night and day. The shop will let you grab fins during the day, but they're closed at night so better to bring your own. It's about 10-12' deep and there are two(!) ladders on the swim deck. This is also where we did our "pool work" for our OW cert.