Southwest of Key West, the snorkeling at Toppino's Reef is considered the most scenic snorkeling dives in the Florida Keys. Also known as the #1 Marker Reef snorkeling dive site, it is well known for its 7 to 10 foot tall coral fingers. It is located about five miles southeast of Key West and 4.5 miles south of Boca Chica Channel.
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 Toppinos Reef 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, Toppinos Reef is the 38th most popular snorkel dive spot of all 40 snorkeling dives in the Florida Keys.