Florida Keys is divided into three different parts – Lower Keys, Middle Keys and Upper Keys.
The Lower Keys begins at Key West and ends at 7 Mi. Bridge, where the Middle Keys takes over from Marathon to Layton. After Middle Keys you will find the Upper Keys, stretching from Islamorada to Key Largo.
One of the best dive sites in the Lower Keys is the Looe Key Reef. Looe Key Reef was appointed national marine sanctuary in 1981 and the marine life is truly amazing and very diverse. Since lobstering is prohibited, you will see more spiny lobsters here than at most other reefs in the area. Looe was a British ship that ran aground on this reef in 1774 and the ship has today became a part of the reef and can be hard to sea if you don’t know what to look for. The most visible signs are a ballast rock pile and an anchor chain in the eastern end of the reef. When Looe ran aground, her commander decided to burn the ship in order to ignite the gunpowder storage. Only by completely destroying her could he prevent the ship from being salvaged by the Spanish.
If you are a beginner, or is doing a check dive, the Middle Keys offers one of the best dive sites in the area – the Sombrero Reef. It’s a shallow dive, but still very interesting and always packed with fish and other marine animals. The depth range is 5 to 35 feet. It’s a spur-and-groove coral reef with impressive finger corals, lettuce corals, gorgonians and soft corals. The wild life at the site includes nurse sharks, big moray, schools of striped sergeant majors, yellowtail snappers, blue parrotfish, barracuda, bar jacks and squirrelfish. Like many other places in the Keys, the Sombrero reef is a Sanctuary Preservation Area. The Sombrero Reef derives its name from the Sombrero Key Lighthouse, a lighthouse built more than 150 years ago.
When you’re visiting the Upper Keys you simply have to check out the dive site called Spiegel Grove. Spiegel Grove is the largest ship ever deliberately sunk to create an artificial reef. It’s a striking 510-foot U.S. Navy Landing Ship Dock and probably the most famous artificial reef in the world. It was sunk in June 2002 and opened to the public on June 2002. Since then it has attracted a great number of divers and snorkelers, but most important – it has attracted an interesting marine flora and fauna as well. The dive is however not for anyone; the dept range is 45 to 130 feet and required skill level intermediate since currents can be unpredictable around the wreck. If you wish do dive into the wreck, you will of course need the specialized equipment and training for diving in an overhead environment. Spiegel Grove is particularly popular for Nitrox dives. The ship is located near Dixie Shoals, approximately 6 miles off Key Largo.
The seasonal changes in Florida Keys are quite big. October to March is considered winter, with water temperatures dropping down to 75 degrees Fahrenheit or lower. The seas are rougher during the winter and generally 3 to 6 feet. A wetsuit is highly recommended if you are to stay any longer period in the water. The summer season begins in April, with water temperatures usually around 85-90 degrees Fahrenheit. You don’t have to wear a wetsuit to stay warm, but a light wetsuit or skins are still recommended as protection against abrasions and jellyfish. The seas are less rough than during the winter, and seldom more than 3 feet.
The reefs in Florida Keys are considered among the best in the world, and fishing restrictions, pollutions controls and diver education are all successful steps that have been taken in order to keep them that way.