The best reef dive sites in the Keys can be found in Key Largo, as this is where John Pennekamp State Park is located. However, Key est has a few great wrecks like the Vandenberg and the Cayman Salvager. These wrecks are part of the Florida Keys Wreck Trek.
Dive boat trips are 2 x daily, one 2-tank morning trip (checkin usually 8 am) and one 2-tank afternoon trip (checkin usually 12:00 noon). The dive boats come back in for lunch, so if you want to do 4 dives a day you will have time to grab a sandwich, or just bring a packed lunch.
You can also opt for a dive guide (extra charge).
The dive sites are all offshore and can only be reached by boat - there is no shore diving.