Southwest of Key West, the snorkeling off Rock Key is popular for its extensive staghorn coral and fire coral in waters with good visibility. There is less live coral here compared to Sand Key. You can expect to see marine life including seargent majors, wrasse, queen angelfish, french angelfish, trumpetfish, damselfish, barracuda, nurse sharks, sea turtles and stingrays in waters from shallows down to 30 feet deep. There are new staghorn coral growths on the western edge of Rock Key.
Rock Key itself is usually exposed at low tide. The best snorkeling at Rock Key is the sand channel thru the middle of the reef. In addition, there are two shallow wrecks to explore on the eastern side of Rock Key. But, keep in mind, the visibility at Rock Key is known to drop dramatically as the waves increase.
To reach the Rock Key Sancturary Preservation Area snorkeling from Key West, you'll need a private charter boat for the half hour excursion. Rock Key is located about 7 miles southwest of Key West and about 1 nautical mile east of Sand Key. A good private boat launch is the Key West Garrison Bight Marina. Rock Key is usually exposed at low tide. Rock Key is located east of Sand Key and west of Eastern Dry Rocks. The southwest buoy is the best for snorkeling.
To reach the snorkeling in Key West, fly into Key West International Airport (EYW), which is served by several airlines including United/Silver Airways, Delta, USAir and Southwest. Alternately, there is also the regular Key West Express ferry service (4 hours) that runs from Ft Myers.
When using a dive boat charter to reach the Rock Key dive site, make sure to reconfirm the reservation the afternoon prior AND the morning prior. Key West snorkeling tour operators are notorious for changing the dive destination just before pulling out of port. Actually, it's kind of comical getting them to commit to which dive site the boat is actually going until you are out of port. The reservation agents will usually treat you as very ignorant and just say they are going to the reef-off-shore, like that's an actual dive site! It is very difficult to pre-reserve a tour to a specific snorkeling dive site. Luckily, the tour companies are all located near each other in the historic Key West wharf and you can just walk-up 45 minutes prior to depature and ask where they are going. Also, keep in mind that most dive boats have a minimum passenger requirement in order to leave dock meaning they may cancel at the last minute, so when reverifying the afternoon prior ask how many reservations they have. And, they may cancel due to wind, so call an hour prior if in doubt.
Overall, Rock Key is the 34th most popular snorkel dive spot of all 40 snorkeling dives in the Florida Keys.