Margaret Brock Reef is a shallow, high-wave-energy reef system located about 5 km west of Cape Jaffa on South Australia's Limestone Coast. Named after the three-masted barque that struck and sank here in 1852, this site is a dedicated sanctuary zone for southern rock lobsters — renowned as one of the best places in SA to see massive, pristine-sized lobsters in their natural habitat. The reef lies in just 2–10 metres of water with scattered wreck remnants (anchors, chains, fittings) visible among the rocky crevices and boulders. High marine productivity makes for thrilling drift snorkels over a reef teeming with life.
Margaret Brock Reef
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Poor conditions. Stay out today.
Showing last known conditions
Wave Height 1.6 mSwell Period 10 sWind Speed 12 knPrecipitation 15 mmTidal Phase slack
Last evaluated
DANGER: Explicit Risks Present
Margaret Brock Reef has hazards marked as danger. Entering the water here means you may face serious risks to your personal safety.
- High Wave Energy / Swell danger
Exposed offshore reef subject to strong Southern Ocean swell and surf, making conditions challenging and unsafe in rough weather.
The spot
Community-maintained
Community contribution: submitted by Daniel
Know before you go
Logged by the community, confirmed by mods
High risk: High Wave Energy / Swell
Exposed offshore reef subject to strong Southern Ocean swell and surf, making conditions challenging and unsafe in rough weather.
Moderate risk: Strong Currents
Tidal and wind-driven currents can sweep snorkelers away from the reef; drift snorkeling awareness required.
Moderate risk: Remote Location
Located 5 km offshore from Cape Jaffa with limited emergency services and marine rescue access.
Low risk: Sharp Reef / Rock
Barnacle-encrusted limestone reef with sharp edges and crevices that can cause cuts if contact is made.
Low risk: Cold Water Temperatures
Southern Ocean waters remain cold year-round (12–18°C); wetsuit exposure risk for extended sessions.
Wildlife Guide
No wildlife notes for this spot yet.
Gallery
1 photo from the community
Getting in
Boat
Entry
The reef lies approximately 5 km west of Cape Jaffa, off the Kingston SE / Limestone Coast region. Boat access is required — launch from Cape Jaffa boat ramp or Kingston SE. The site is exposed and should only be attempted in calm conditions with local knowledge.
Parking & facilities
Parking available at the Cape Jaffa boat ramp area.
parkingboat_ramp
No direct fees for snorkeling. A marine park permit may be required for nearby sanctuary zones — check SA Marine Parks regulations.
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Gallery ┬╖ 1 photos
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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