The Blowhole sits at Thunder Point on the south-east tip of Lady Julia Percy Island — Australia's only offshore volcano and home to the largest Australian fur seal colony in the southern hemisphere. This advanced dive site features a dramatic 18-metre opening that leads into a magnificent cave system deep beneath the island. When swell conditions are flat and calm, the underwater cave reveals otherworldly basalt formations carved by ancient volcanic activity. Above water, the blowhole blasts streams of seawater skyward; below it, few have ever ventured into the cathedral-like cavern. The island itself (Deen Maar) is culturally sacred to the Eastern Maar and Gunditjmara peoples and is only accessible by boat from Port Fairy.
Blowhole (Lady Julia Percy Island)
AdvancedMAYBE
MAYBE
Fair. Experienced snorkellers only.
Showing last known conditions
Wave Height 1.1 mSwell Period 11 sWind Speed 12 knPrecipitation 21 mmTidal Phase slack
Last evaluated
DANGER: Explicit Risks Present
Blowhole (Lady Julia Percy Island) has hazards marked as danger. Entering the water here means you may face serious risks to your personal safety.
- Swell-dependent access danger
The Blowhole is only diveable / snorkelable in extremely flat, calm conditions with zero swell. Swell makes the site dangerous and the cave inaccessible.
- Cave entanglement risk danger
The 18-metre underwater cave opening can disorient snorkelers and divers. Strong surge inside the cave system increases risk of entanglement or impact with basalt walls.
The spot
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Community contribution: submitted by Daniel
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High risk: Swell-dependent access
The Blowhole is only diveable / snorkelable in extremely flat, calm conditions with zero swell. Swell makes the site dangerous and the cave inaccessible.
High risk: Cave entanglement risk
The 18-metre underwater cave opening can disorient snorkelers and divers. Strong surge inside the cave system increases risk of entanglement or impact with basalt walls.
Moderate risk: Remote offshore location
Lady Julia Percy Island is 8 km offshore in Bass Strait. Emergency rescue is extremely difficult; boat support is mandatory.
Moderate risk: Strong currents and surge
Bass Strait currents and Southern Ocean swells create unpredictable surge around Thunder Point, especially near the blowhole opening.
Low risk: Cold water temperatures
Southern Ocean waters around the island are cold year-round (10–16°C), increasing risk of hypothermia without proper exposure protection.
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Getting in
Boat
Entry
The Blowhole is located on the south-east end of Lady Julia Percy Island, approximately 8 km off the coast of western Victoria. Boat tours and charters depart from Port Fairy (pier/boat ramp). The island itself is not open to public landing. GPS: -38.425871, 141.998482.
Parking & facilities
Parking available at Port Fairy boat ramp/pier area. Arrive early as spaces fill during peak season.
parkingtoilets
No fee to view from the water, but boat charter/tour fees apply. Typical scenic tour rates from Port Fairy operators.
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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