

Thetford Reef sits on the outer Great Barrier Reef and offers an unusually varied underwater landscape for beginner divers, combining a shallow reef top, a canyon, and a drop-off that descends to 30 metres. You'll spend most of your time in the 5 to 15 metre range where visibility regularly reaches 15 to 30 metres. Currents are mild, which helps you drift gently along the reef without much effort. Keep an eye out for sea turtles grazing on the reef, giant clams wedged into coral heads, clownfish tucked into anemones, and rays cruising the sandy bottom. Reef sharks, trevally, mackerel, and tuna pass through the deeper water along the drop-off.
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The months from May to October bring calmer seas and the clearest visibility, making them the most reliable time to book. Scan the water around the boat before you enter, as jellyfish can drift into the area and boat traffic requires you to stay close to your guide when surfacing.
Thetford Reef is accessible via a 90-minute boat trip from Cairns. Several tour operators, such as Passions of Paradise, Silverswift, and Pro Dive, run day trips and liveaboards to the site from the Reef Fleet Terminal in Cairns.
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Stinger (jellyfish) season is from November to May. Wearing a full-body stinger suit is highly recommended during these months. While reef sharks are present, they are generally not aggressive.
Depth
5-30m
Visibility
8-40m
Skill Level
Beginner
Entry
Boat
Boat required
Water Temp
23-30°C
Current
Mild
Typical Dive
45 min
Best Time
May, Jun, Jul, Aug, Sep, Oct
Thetford Reef near Cairns, Queensland offers diving from 5 metres to 30 metres depth. The shallow sections begin at 5 metres, making it accessible for beginners, whilst more experienced divers can explore the deeper walls reaching 30 metres. This varied depth profile allows divers of different skill levels to explore the same reef system during a single boat trip.
Thetford Reef is suitable for beginner divers with Open Water certification. The site features shallow areas starting at 5 metres depth and mild currents, providing ideal conditions for less experienced divers. Guided tours and equipment rental are available through boat charters operating from Cairns.
Thetford Reef hosts diverse marine life including sea turtles, reef sharks, rays, giant clams, and schools of mackerel and tuna. Divers regularly encounter clownfish amongst anemones and colourful parrotfish grazing on the coral. The reef's varied depths from 5 to 30 metres support different species across its topography.
The best months to dive Thetford Reef are May through October, coinciding with Australia's dry season. During these months, water temperatures range from 23 to 30 degrees Celsius and visibility reaches 15 to 30 metres. Conditions are generally calmer with reduced jellyfish activity compared to the wet season.
Thetford Reef is accessed exclusively by boat from Cairns, Queensland. Boat charters depart regularly from Cairns Marina and the journey typically takes 60 to 90 minutes. All diving must be boat-based as there is no shore access to this outer reef location.
Night diving is available at Thetford Reef through specialised boat charters from Cairns. Night dives reveal different marine behaviour including hunting reef sharks, sleeping parrotfish in mucus cocoons, and nocturnal crustaceans. Divers must hold appropriate night diving qualifications and arrange this activity in advance with charter operators.
An Open Water certification is required to dive Thetford Reef. This entry-level qualification allows divers to explore the reef's depths from 5 to 30 metres under appropriate supervision. All boat charter operators from Cairns will verify certification cards before allowing divers to enter the water.
The main hazards at Thetford Reef include jellyfish (particularly during summer months), boat traffic from multiple charter vessels, and the presence of reef sharks. Divers should wear protective suits during jellyfish season, maintain awareness of surface boat activity, and respect marine life by keeping a safe distance from sharks. Mild currents require standard buoyancy control skills.
Yes, equipment rental is available at or near Thetford Reef in Cairns. Contact local dive operators for specific gear availability and prices.
A 3mm wetsuit is recommended for diving at Thetford Reef in Cairns. Water temperatures range from 23°C to 30°C.