Meet the site
The Cod Hole is one of the two or three sites every diver who visits Julian Rocks wants to do, a genuine swim-through or arch cut through the rock at the northern/eastern end of the island where the more exposed, current-swept side of the reef begins. The entrance sits around 15 to 18 m and the passage slopes down through the rock to a sandy floor at 20 to 22 m, wide and tall enough to swim through in comfort rather than squeeze through, which is what makes it accessible to Advanced Open Water divers rather than being reserved for technical specialists. Grey nurse sharks are the headline attraction from roughly May to October, when a rotating population of these placid, toothy-looking but harmless sharks uses the cavern and the surrounding walls as a daytime resting spot, hanging motionless in the current with their mouths open in a way that unsettles new divers until they realise the sharks have no interest in them at all. Even outside shark season the swim-through and the sand beyond it are consistently good for large animal encounters: moray eels sit in cracks along the walls, big blue gropers cruise past, schools of bullseyes and kingfish move through the passage, and the sandy bottom beyond the cave regularly holds larger pelagic visitors working the current line. Turtles are common on the approach and departure. Because it sits on the more exposed side of Julian Rocks, the Cod Hole cannot always be run — a strong easterly or southerly swell will push too much surge through the passage to dive it safely, and operators will substitute the Nursery or Hugo's Trench on those days. When conditions are right, though, this is regarded as one of the best temperate/subtropical swim-through dives on the entire east coast, combining genuine cavern topography with one of the most reliable grey nurse shark encounters south of the tropics, and it is the dive most repeat Julian Rocks visitors specifically request.
Research this site before booking Stored site notes may be historical. These questions highlight gaps without turning old instructions into a current dive plan.
Julian Rocks – Cod Hole is recorded as Cave/Cavern in Tweed & Byron Bay. The listed access is boat. Confirm the actual meeting point, route and permission to visit; a map pin does not establish any of these.
Topics flagged by the stored research
These are questions prompted by the existing notes, not a verified or complete hazard assessment.
- Current and timing
- Ask how the operator assesses the current window for the actual route. Historical tide notes are not a departure instruction.
- Planned depth
- Confirm the intended route and training requirements; the recorded maximum is not a target.
- Water movement
- Ask how swell and local exposure affect the proposed entry, exit and route.
- Overhead environments
- Ask whether the plan stays entirely in open water. A wreck or cave listing is not permission or training to enter.
Historical access notes exist for this record, but have not been independently verified for current use. Request current directions from the operator or site manager rather than following an old entry description.
Questions, answered
Is Julian Rocks – Cod Hole suitable for my certification?
The record lists Advanced Open Water. That does not establish suitability for every route or day. Share your training, recent experience and equipment needs with the operator and ask about the specific proposed dive.
Can I book Julian Rocks – Cod Hole through YouDive?
YouDive is an independent research directory. Contact an operator directly to confirm whether it currently runs the trip, the inclusions and the booking terms.
What you might see
Grey nurse sharks, wobbegongs, moray eels, blue groper, black cod, bullseyes, turtles, kingfish, large pelagics on the sand
Location
At the end of the island on its more exposed side, a spectacular swim-through/arch beginning around 15-18 m and dropping to a sandy bottom near 20-22 m, one of the signature dives at Julian Rocks.
Before you make plans
Conditions, access and operator schedules can change. This is a location guide, not a dive plan. Ask a local operator about current conditions and suitability for your training and experience.
Sources & further reading
byronbaydivecentre.com.audiveplanit.comabyss.com.ausundive.com.ausundive.com.auadreno.com.auRecord updated 26 Sept 2026. Source claims are being reviewed.