Four Mile Reef is an iconic offshore dive and snorkel site sitting roughly 4 nautical miles off the Busselton coast in Geographe Bay, within the Ngari Capes Marine Park (Southwest Capes, WA). The reef features a dramatic 1-metre shelf drop to 17–18 metres, beneath which lies an underwater oasis of sponge gardens, ledges, and rocky overhangs. Accessible only by boat, this offshore limestone reef offers clear bay waters and a thriving ecosystem that attracts both serious snorkelers and divers. Its exposed position means conditions can change quickly, rewarding calm-weather visits with exceptional visibility.
Four Mile Reef
IntermediateGO
GO
It's a go.
Showing last known conditions
Wave Height 0.3 mSwell Period 11 sWind Speed 0.7 knPrecipitation 1.2 mmTidal Phase ebb
Last evaluated
The spot
Community-maintained
Community contribution: submitted by Daniel
Know before you go
Logged by the community, confirmed by mods
Moderate risk: Boat traffic
Offshore reef accessed only by boat; vessels transit the area and snorkelers must be visible on the surface.
Moderate risk: Strong currents
Geographe Bay can experience tidal flows and wind-driven currents that affect the exposed reef area.
Low risk: Depth hazard
Reef drops from 1 m shelf to 17–18 m; less experienced snorkelers should stay within the shallower shelf zone.
Low risk: Changing weather
Offshore position means conditions can deteriorate rapidly with wind shifts, creating chop and reduced visibility.
Wildlife Guide
No wildlife notes for this spot yet.
Gallery
Be the first to share a photo
No photos yet — yours could be the first.
Photos are reviewed by moderators before they appear.
Getting in
Boat
Entry
Four Mile Reef lies approximately 4 nautical miles offshore from Busselton, Western Australia. Launch from Busselton Jetty boat ramp or Busselton Boat Harbour. The reef is located in Geographe Bay within the Ngari Capes Marine Park. GPS coordinates approximate: 33°33'S, 115°03'E.
Parking & facilities
Parking available at Busselton Jetty precinct and Busselton Boat Harbour ramps. Arrive early on summer weekends as lots fill quickly.
parkingtoiletsboat_ramp
No direct entry fee for the reef, but boat launch fees may apply at Busselton Boat Harbour. Marine park entry is free.
Spot Map
Community
Trust
Is this spot real, accurate, still loved?
Spots near Western Australia
No nearby spots yet.
Needs verification
Quick verify
One tap helps the community keep this spot honest.
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