One Tree Reef is a pristine, 5.5 km by 3.5 km lagoonal platform reef in the southern Great Barrier Reef, crowned by the tiny One Tree Island coral cay. This remote, research-only reef is part of the Capricornia Cays National Park and hosts a University of Sydney research station. Its shallow lagoon, back-reef sand apron, and rhodolith beds support vibrant coral formations and exceptional water clarity. The reef is a critical seabird breeding site and offers world-class snorkeling amid pristine coral gardens — though access is highly restricted, preserving its untouched condition.
One Tree Reef (Keppel Islands)
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Wave Height 0.3 mSwell Period 6.2 sWind Speed 5.9 knPrecipitation 0.0 mmTidal Phase flood
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Community contribution: submitted by Daniel
Know before you go
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Moderate risk: Stinger season (jellyfish)
Marine stingers (box jellyfish and Irukandji) are present in the southern Great Barrier Reef waters, particularly during the warmer months.
Moderate risk: Remote location — limited medical access
As a research-only zone with limited facilities, medical evacuation is difficult and slow. The island is remote with no full-time medical staff.
Moderate risk: Strong tidal currents
The reef is exposed to the open ocean and strong tidal flows through the lagoon channel can sweep snorkelers off course.
Moderate risk: Marine stingers (box jellyfish)
Box jellyfish and other stingers are present in the southern Great Barrier Reef waters, particularly during the warmer months.
Low risk: Tidal currents
The reef is subject to tidal currents that can be strong around the reef edge and channels, especially during spring tides. Snorkellers should be aware of changing tides.
Low risk: Sharp coral
Exposed coral can cause cuts and abrasions. Snorkellers should avoid touching coral and wear protective footwear.
Low risk: Sharp coral rubble
Sharp coral rubble and shingle cay shoreline can cause cuts and abrasions.
Low risk: Intense sun exposure
Extreme sun exposure with limited shade on the cay and reef flat.
Wildlife Guide
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Gallery
1 photo from the community
Getting in
Boat
Entry
One Tree Reef is located approximately 96 km east-northeast of Gladstone, Queensland. Access is by private or chartered vessel only. The reef is part of the Capricornia Cays National Park and is a protected scientific research zone managed by the University of Sydney — general public access is restricted and requires permits. Most visitors access the southern Great Barrier Reef via boat tours from Gladstone or Great Keppel Island.
Parking & facilities
No parking available — the reef is offshore. Park at Gladstone marina or Rosslyn Bay if chartering a vessel from the mainland or Great Keppel Island ferry terminals.
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About this data
- Conditions last evaluated
- Spot data last updated
- Data sources
- Open-Meteo (marine & weather conditions), tide predictions via UTide, community contributors (descriptions, hazards, marine life).
- License
- Spot content licensed under CC BY-SA 4.0. How's the Spot is open source.
Weather & swell ┬╖ Open-Meteo marine & weather APIs Tides ┬╖ UTide harmonic analysis Sea & safety ┬╖ community reports