Sombrero Reef is the largest reef in the Middle Keys, marked by a historic lighthouse. The site features a classic spur-and-groove topography with high coral relief. Divers and snorkellers can explore depths ranging from 2 to 35 metres, with an average depth of 20 metres. Marine life commonly observed includes Great Barracuda, Blue Tang, Stoplight Parrotfish, Purple Sea Fan, and various wrasses. Less frequently, visitors may encounter Queen Angelfish, French Angelfish, Hogfish, and Scrawled Filefish. Conditions are generally mild, though divers should remain aware of boat traffic and surge. The site is accessible only by boat and is suitable for beginners.

Marquesas Keys features a combination of natural reef and artificial structures located 16 kilometres from shore. The site ranges in depth from 5 to 30 metres, with an average of 15 metres, making it suitable for intermediate divers. Boat access is required, and divers should be prepared for moderate currents that can intensify at depth. Visibility varies between 5 and 25 metres. Hazards include jellyfish, sharks, sharp coral, and strong currents. Divers are advised to maintain buoyancy control and consider wearing gloves to protect against sharp surfaces. A typical dive lasts 45 minutes, and water temperatures range from 23C to 29C throughout the year.

Samantha's is a shallow reef site in Islamorada, United States, with depths ranging from 5 to 8 metres. This site is suitable for beginner divers and offers a relaxed environment with mild currents. Visibility typically spans 5 to 10 metres, allowing for observation of the reef structure. Divers should maintain good buoyancy control to avoid contact with sharp coral and rocks on the seabed. Access is by boat only, and the site is suitable for night diving. Species recorded around this area include various angelfish, wrasses, parrotfish, and invertebrates such as purple sea fans.

Horseshoe Reef is a shallow marine reef located 1300 metres from the shore of Islamorada. The site features an average depth of 5 metres, with a range between 3 and 6 metres, making it suitable for beginners. Access to the reef is by boat only. Divers and snorkellers should be aware of potential hazards including boat traffic, sharp coral, surf, and strong currents. Conditions at the site are variable, with visibility typically ranging from 5 to 10 metres. Water temperatures fluctuate throughout the year, ranging from 24C in the winter months to 30C during the summer.

Hermans Behind is a reef site located in Islamorada, United States. The site features a depth range of 5 to 20 metres and is accessed by boat. Divers can expect mild currents and visibility reaching 30 metres. The moderate depth profile provides a comfortable environment for those building confidence in open water. Water temperatures fluctuate between 23C and 29C throughout the year. As conditions and facilities at this location can vary, divers should confirm charter arrangements and local site status in advance of their trip.

Sombrero Beach offers a combination of natural and artificial reef structures, providing two distinct environments for divers. Located near Islamorada, the site features depths ranging from 3 to 10 metres with an average of 6 metres, making it suitable for beginners. Visibility typically spans 10 to 30 metres, supported by mild currents. Access is by boat, and the site is suitable for night diving. Divers should remain vigilant regarding boat traffic in the area and are advised to deploy a surface marker buoy before ascending. Full facilities, including a dive shop, showers, and changing rooms, are available nearby to support your dive.

Horseshoe Reef is a shallow reef structure located at Alligator Reef, maintaining a consistent depth of 6 metres. This site is suitable for beginners, though the moderate current requires careful planning and coordination with your boat captain. Visibility typically ranges from 5 to 10 metres. Access is by boat only, and divers should remain vigilant regarding boat traffic by using a surface marker buoy. Water temperatures are warm throughout the year, ranging from 25 to 30 degrees Celsius. Divers should avoid contact with the reef structure to prevent injury from sharp coral and rocks, and remain observant of the surrounding area.

Coffins Patch is a shallow reef located near Alligator Reef in the United States. The site features depths ranging from 2 to 9 metres, with an average depth of 5 metres, making it suitable for beginner divers. Access is strictly by boat, and divers should remain near their vessel due to the potential for currents. Visibility at the site typically ranges from 10 to 30 metres. Water temperatures remain between 25 and 29 degrees Celsius throughout the year. Divers should be aware of variable conditions, including the possibility of strong currents and surf, and confirm current status with their boat operator before entry.