Lehua Crater is a diverse marine site located off the coast of Niihau, United States. The topography encompasses reef slopes, caves, drop-offs, and artificial reef structures. Divers can explore depths ranging from 15 to 70 metres, with an average depth of 45 metres. Visibility is high, typically spanning 29 to 91 metres. Access is strictly by boat to avoid surf and shore break hazards. Conditions generally feature mild currents, though stronger surges may occur. Due to the depth and potential for entanglement, divers should carry a cutting tool and reef hook. This site is suited for intermediate divers, with typical dive times lasting 60 minutes.

Arches is an advanced open-water dive site located off Niihau, featuring a complex topography of reef, wall, cavern, and drop-off structures. Divers navigate depths ranging from 10 to 32 metres, with an average depth of 25 metres. The site is characterised by strong currents and visibility between 30 and 40 metres. Due to the presence of overhead environments within the caverns and significant depth profiles, this site requires advanced buoyancy control and careful gas management. Access is strictly by boat to avoid dangerous surf and shore break zones. Divers should be prepared for potential boat traffic upon surfacing and carry a surface marker buoy.

Pinnacles is a remote offshore reef located 27 kilometres from the coast of Niihau. This site features a pinnacle formation suitable for advanced divers due to the strong currents and deep water. Divers can expect depths ranging from 14 to 40 metres, with an average depth of 23 metres. Visibility is consistently recorded at 30 metres. Access is strictly by boat charter, and guided tours are available for this drift dive. Given the exposure and current, this site is intended for experienced divers only. Water temperatures fluctuate between 22C and 26C throughout the year.

South Shore is a boat-access dive site located off Niihau, featuring a diverse underwater topography of reefs, drop-offs, walls, and pinnacles. The site offers consistent visibility of 30 metres. Divers should be prepared for moderate currents that can shift quickly, requiring solid buoyancy control and situational awareness. With depths reaching 20 metres, this site presents significant hazards including strong currents, deep water, and the presence of sharks. All gear and hydration must be managed on the boat, as there are no facilities on site. Due to the challenging conditions, this location is best suited for experienced divers who can maintain awareness throughout the 60-minute dive duration.

Mana Crack is an 11-mile long sunken barrier reef located off the coast of Niihau. As the furthest offshore dive site in Hawaii, it features numerous drop points along its length. Due to the absence of moorings and the presence of strong currents, this site is strictly for advanced divers and is accessed exclusively via live boat dives. Visibility at the site varies, ranging from 1 to 30 metres. Water temperatures remain consistent throughout the year, typically between 24C and 27C. Divers should be prepared for challenging conditions at this remote offshore location.

Nualolo Kai is a reef site located along the Na Pali Coast of Kauai. Accessible only by permitted boat tours, the area features an ancient Hawaiian village site on the adjacent shore. The reef environment is suited for intermediate divers and snorkellers, with depths ranging from 3 to 7 metres and an average depth of 5 metres. Conditions include mild currents and visibility typically between 6 and 10 metres. Water temperatures remain consistent throughout the year, ranging from 24 to 27 degrees Celsius. Divers and snorkellers should be aware of potential hazards including boat traffic, rip currents, sharp coral, and surf.

Hale O Honu, also known as the House of Turtles, is a reef site in Kauai featuring 11 moorings spread across 8 acres. The topography consists of sand, lava crevices, and outcroppings. Divers can expect depths ranging from 6 to 20 metres, with an average depth of 12 metres. Access is by boat only. Conditions are generally mild with visibility around 15 metres. Divers should be aware of potential hazards including sharp coral and surge. This site is suitable for beginners.