Australia · Great Barrier Reef
Cod Hole
Popular northern reef season with dry weather and strong visibility.
The Cod Hole is the most famous dive site on the northern Great Barrier Reef — a sand bowl populated by huge potato cod (giant grouper) that swim up to divers. Combined with Osprey Reef and the Ribbon Reefs on a typical liveaboard.
Good season
October–December is peak with warm water and minke whales (June–July). Year-round divable.
Trip duration
4–7 night liveaboard from Cairns or Port Douglas.
Dive style
Reef and pinnacle diving with moderate current; sand-bowl interaction at the Cod Hole.
Dive level
Open Water for Cod Hole; Advanced for Osprey Reef and deeper sites.
Reef health
What you’ll actually findSome loss since the 2010s, but the reef still has plenty to dive. Pick depth and shoulder-season carefully.
Coral reef health
How is this calculated?Heat stress right now
No abnormal heat right now. Corals stay coloured.
NOAA Coral Reef Watch · updated May 2026 · 0.5 °C-week heat dose
What to expect on a dive
Northern GBR is holding up better than the mid and southern sectors. Expect full reef colour and the resident potato cod. Less crown-of-thorns pressure than further south.
Sources, methodology, and the raw numbers
Raw observed numbers
- Coral cover: 33% (survey Aug 2024, AIMS LTMP manta-tow + photo-transect)
- Bleached: 12%
- Recent mortality: 4%
- Cooler-than-average late-summer SSTs in 2024 limited bleaching impact on the Northern GBR's Ribbon Reefs.
Raw thermal numbers
- NOAA CRW alert level: No stress
- Degree Heating Weeks: 0.5 °C-wk
- SST anomaly: +0.9 °C
How we summarise this
Observed coral cover, bleaching, and mortality come from named in-situ surveys with a stated date and method — they describe one snapshot of one reef and do not extrapolate to neighbouring sites. Current thermal stress is satellite-derived from NOAA Coral Reef Watch at ~5 km resolution; it indicates risk, not observed coral damage. We deliberately separate observed condition, current thermal stress, and projection — and we never publish a projection without a documented model and uncertainty.
Sources
- AIMS Long-Term Monitoring Program — Australian Institute of Marine Science
- Great Barrier Reef Marine Park Authority — Australian Government
- NOAA Coral Reef Watch — U.S. National Oceanic and Atmospheric Administration
- Global Coral Reef Monitoring Network — GCRMN / ICRI
- Atlantic and Gulf Rapid Reef Assessment — AGRRA Program / Perry Institute for Marine Science
- NOAA National Coral Reef Monitoring Program — NOAA Coral Reef Conservation Program
- Reef Check — Reef Check Foundation
- NOAA CoastWatch / OceanWatch — NOAA NESDIS / STAR
- Allen Coral Atlas — Arizona State University Center for Global Discovery and Conservation Science
- International Coral Reef Initiative — ICRI Secretariat
- Reef Life Survey — Reef Life Survey Foundation
- NASA PO.DAAC — NASA Jet Propulsion Laboratory / Caltech
- Copernicus Marine Service — Mercator Ocean International for the European Union
- NASA Ocean Color (OB.DAAC) — NASA Goddard Space Flight Center / Ocean Biology Processing Group
- Argo float network — International Argo Program / UCSD
- CoralWatch — University of Queensland
- IMOS / AODN — Integrated Marine Observing System / Australian Ocean Data Network
- WRI Reefs at Risk Revisited — World Resources Institute
- Ocean Health Index — OHI partnership (Conservation International + UCSB + NCEAS)
- IPCC Special Report on the Ocean and Cryosphere (SROCC) — Intergovernmental Panel on Climate Change
- GOA-ON — Global Ocean Acidification Observing Network — GOA-ON Secretariat + IOC-UNESCO
- HAEDAT — Harmful Algae Event Database — IOC-UNESCO Intergovernmental Panel on Harmful Algal Blooms
- NCEI Marine Microplastics — NOAA National Centers for Environmental Information
Reef condition changes year to year. If you visit, consider supporting responsible-travel and conservation operators on the ground.
Pressure on this reef
Protection · fishing · what you can doProtected-area status
No-take reserveFully no-take — no fishing of any kind. The strongest protection tier.
Fishing pressure
Low fishing pressureDominant pressures
- agricultural runoff from inshore catchments
- warming
- cyclones
5 Green Fins-verified operators known at this location.
What you can do
GBR Marine Park is zoned no-take in Marine Park 'green zones'. The biggest pressure here is land-based runoff from Queensland farming — diving low-impact and supporting reef-restoration initiatives helps.
Protection status sourced from Protected Planet / WDPA and refined with Marine Protection Atlas. Fishing pressure proxy is Global Fishing Watch AIS data. See the methodology for what these sources can and can’t prove.
Pollution & water-quality
What divers should knowAgricultural runoff from Queensland
CONCERNINGSince ongoing
Inshore Great Barrier Reef receives runoff from sugarcane and banana plantations, especially after wet-season rains. Northern outer-reef sites (where Cod Hole sits) are largely buffered.
Crown-of-thorns starfish outbreaks
CONCERNINGSince 2010
Cyclical COTS outbreaks driven partly by nutrient runoff. AIMS-led culling teams operate at affected reefs.
What this means for your trip
Outer Ribbon Reef sites are buffered from coastal pressures and remain in good shape. Inshore-reef trips are more affected by runoff and clarity issues.
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Gear
What to bringWhat divers say
“A 60kg potato cod gently bumping your fin is the most personable interaction I've ever had on a reef.”