Lady Julia Percy Island (Deen Maar) is Australia's only offshore volcano — a rugged basalt fortress rising from Bass Strait, 8 km off Victoria's coast. The leeward (eastern) side offers relative shelter from prevailing south-westerly swells, where underwater terrain drops from 5 to 25 metres across boulder gardens, rocky reefs and bommies. This remote, boat-only site sits beside a thriving Australian fur seal colony, with sea caves, encrusted ledges and kelp forests creating a dramatic seascape. The island is a State Faunal Reserve, so expect pristine conditions and abundant wildlife in a truly wild setting.
Lady Julia Percy Island (Deen Maar) - Leeward side dive site
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Wave Height 2.5 mSwell Period 11 sWind Speed 2.3 knPrecipitation 32 mmTidal Phase slack
Last evaluated
DANGER: Explicit Risks Present
Lady Julia Percy Island (Deen Maar) - Leeward side dive site has hazards marked as danger. Entering the water here means you may face serious risks to your personal safety.
- Remote location danger
The island lies 8 km offshore with no facilities, shelter or emergency services. Self-sufficiency and marine radio/EPIRB are mandatory.
The spot
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Community contribution: submitted by Daniel
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Logged by the community, confirmed by mods
High risk: Remote location
The island lies 8 km offshore with no facilities, shelter or emergency services. Self-sufficiency and marine radio/EPIRB are mandatory.
Moderate risk: Open ocean swell exposure
Despite being on the leeward side, the site is exposed to Bass Strait swells which can build suddenly. Calm conditions are essential.
Moderate risk: Strong currents and rips
Tidal flows around the island can produce strong currents, particularly on changing tides. Drift diving conditions are possible.
Moderate risk: Strong ocean swells
The island sits exposed in Bass Strait with large Southern Ocean swells rolling in year-round, making conditions highly variable even on the leeward side.
Moderate risk: Strong currents and surge
Tidal currents and wave surge around the island can be powerful, especially when swells wrap around the headlands.
Low risk: Restricted access (State Faunal Reserve)
Landing on the island requires a permit. Snorkeling/diving must be done from an authorised boat charter.
Low risk: Cold water temperatures
Bass Strait waters range from 12–18°C year-round. Thick wetsuit or drysuit required.
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Getting in
Boat
Entry
The island lies 8 km off the coast near Yambuk, about 21 km south-west of Port Fairy. Boat trips depart from Port Fairy Harbour. The leeward dive site is on the eastern side at -38.4126, 142.0018.
Parking & facilities
Parking available at the Port Fairy boat ramp precinct off Gipps Street, Port Fairy.
parkingboat_ramp
Join a licensed charter from Port Fairy (~$100–$200 pp). Independent landing requires a Parks Victoria permit.
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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