Horseshoe Reef

Horseshoe Reef is a reef dive site off the south coast of Oʻahu, Hawaiʻi, named for its two distinct horseshoe-shaped reef formations built on lava rock. The reef runs from 40 to 65 ft (12–20 m), with a maximum depth of around 65 ft (20 m), and its terrain features coral channels, reef ledges, and playful topography. From the main reef, a 50 ft (15 m) swim reaches the adjacent Kewalo Pipe, an old storm drain that runs out to sea and is itself covered in coral.

Marine life at Horseshoe Reef includes several species of eels, pincushion starfish, and antler coral, along with yellowtail coris, rock-mover wrasse, and Sergeant Major fish — the latter often seen guarding vibrant purple egg patches. Spotted eagle rays are sometimes seen off in the distance. Just beyond the main reef, a nearby area known as Secret Reef hosts a turtle cleaning station and sleeping whitetip reef sharks. Dragon morays have been spotted at night.

Visibility is typically up to 100 ft (30 m), with the clearest conditions during the summer months. Water temperature ranges from around 75°F (24°C) in winter (January–March) to 80°F (27°C) in summer (July–September), and a 3 mm wetsuit is comfortable year-round. The site can be dived in any season.