Offshore of Lower Matecumbe Key, the snorkeling at Indian Key is known for its coral formations and diverse marine life. The island is an old coral reef. The waters and rocky shores of Indian Key Sanctuary Protection Area are only accessible by kayaking or dive boats. There is good snorkeling off the south and east sides of the island. The waters are quite shallow and rocky, so be careful - high tide might be a good time to snorkel here. The local dive shops may discourage you from snorkeling, but that might be since they want you to purchase a boat tour to the outer reef instead.
The Indian Key State Park is offshore of US1 at milepost 78.5 on the ocean side. It is a 25 minute sea kayak trip from Robbies Marina. The best snorkeling can be found on the east and south sides of the island where there is shallow coral and seagrass providing habitat for spiny lobster, starfish and sponges.
Note: All Indian Key snorkeling must be conducted at least 100 feet from the dock at all times, and all snorkeling requires a Diver-Down flag. There are no facilities on the island.
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.
Overall, Indian Key State Park is the 7th most popular snorkel dive spot of all 40 snorkeling dives in the Florida Keys.