By Water 24.453501, -81.876482
Sand Key is a great place for relaxing and enjoying calm waters. It is well known as a first-class site for snorkeling but also has good diving on the ocean side. For beginners, it is best to stick to the northwest portion of the key. Sand Key is easy to find and is seven miles southwest of Key West. The key is a sand-spit of an island and is marked by a 110-foot light tower. Note that when diving or visiting this site, no anchoring is allowed so boats should tie to a mooring buoy (there are 24 on this site).
Information from Divespots.com