The Vernon Islands, located off the Darwin Coast, offer a challenging environment featuring both reef systems and blue holes. Depths range from the shallows down to 60 metres, requiring intermediate to advanced skill levels. The area is defined by significant tidal variations and strong currents, which can create horizontal waterfalls at low tide. Divers must navigate these conditions, and timing dives around slack water is essential. Visibility typically ranges between 10 and 25 metres. Due to the presence of crocodiles, dangerous jellyfish, and strong currents, diving with experienced local operators is required. A full exposure suit is recommended for protection against stingers.

Vernon Islands Blue Holes are a series of blue hole structures located off the Darwin Coast. The site features a reef environment that drops from the shallows to depths of 60 metres. Due to the location, the area is subject to strong tidal races, eddies, and upwellings, with currents reaching 2.5 knots. Visibility typically ranges between 15 and 25 metres. Water temperatures are warm, ranging from 26C to 31C throughout the year. Access is strictly by boat, and the site is suited for advanced divers and snorkellers. Hazards include strong currents, potential for decompression, and the presence of box jellyfish and saltwater crocodiles.

Vernon Islands Blue Holes are a series of reef structures and blue holes located off the Darwin Coast. This site is defined by massive tidal movements that create horizontal waterfalls over the reef flats. Diving and snorkelling are restricted to slack tide during neap tides due to strong currents. Depths range from 5 to 40 metres, with a thermocline present where deeper water is noticeably cooler than the surface. Access is by boat only, and the site is suited for intermediate divers experienced in drift conditions. Saltwater crocodiles are a potential hazard in these coastal waters. Conditions are most reliable between May and October.

Cape Hotham is a remote boat-access site on the Darwin Coast, defined by its challenging conditions and structural features. The topography includes a blue hole formation and established coral structures shaped by the environment. Divers must be prepared for strong tidal currents that frequently affect the area. Visibility is variable, and the site is strictly for advanced divers capable of managing moving water. Hazards include significant boat traffic, the presence of saltwater crocodiles, and a high risk of box jellyfish, particularly between November and May. Local intelligence regarding current conditions and recent crocodile sightings is essential before planning any activity at this location.

Lee Point Sponge Reef, located off the Cox Peninsula, is a natural reef system characterised by its sponge communities. This site is accessible via both shore and boat entries. Divers should note that Darwin experiences significant tidal movements between 1.5 and 8 metres, which can generate mild to strong currents and rips. Water temperatures remain warm throughout the year, ranging from 26C to 31C. Due to the presence of saltwater crocodiles and seasonal venomous jellyfish, extreme caution is advised. Facilities including parking, toilets, and showers are available on site. The reef is best visited during the dry season, particularly around high slack tide for improved visibility.

Casuarina Beach on the Cox Peninsula is a shallow shore-entry site featuring reef and seagrass habitats. It is suitable for beginners seeking a gentle introduction to coastal exploration. Water temperatures remain warm throughout the year, ranging from 26C to 31C. Visitors should be aware of significant hazards, including saltwater crocodiles and jellyfish. The official stinger season runs from October to May, and swimming is not advised during this period. Species recorded around this area include mullet, snails, and various crustaceans. Always check Northern Territory crocodile and marine stinger alerts before entering the water, as conditions and risks change throughout the year.

Dripstone Cliffs on the Cox Peninsula offers a shore-entry reef dive suitable for intermediate divers. The site features a mix of natural and artificial reef structures along the northern shoreline. Divers must respect the significant tidal range of the Darwin area, which can generate moderate to strong currents; timing dives around tidal slack is essential. Water temperatures remain consistently warm, ranging from 26C to 31C throughout the year. Hazards include rip currents, crocodiles, and jellyfish, particularly during the Wet Season from October to May. Parking is available at the site. Snorkelling is possible but rated 2/5 due to the challenging tidal conditions.

Nightcliff Beach is a shallow shore dive and snorkel site on the Cox Peninsula, with depths ranging from 1 to 3 metres. The site features coral formations and is suited for intermediate divers due to challenging conditions. The Darwin region experiences significant tidal movements of up to 8 metres, which generate strong currents, sweeps, and rip currents. Visibility is highly variable, typically between 1 and 8 metres. Water temperatures remain warm throughout the year, ranging from 26C to 31C. Facilities at the site include parking, toilets, and showers. Due to the presence of crocodiles, sharks, and venomous jellyfish, extreme caution is required and swimming is generally not recommended.