Meet the site
The Outer Transit Caves are the natural-reef counterpart to the famous wrecks on Transit Reef. The seaward face of the reef is undercut into limestone swim-throughs, arches and overhangs in shallow water, and the marinelife.org.au site guide notes that visibility here is often excellent, sometimes better than on the wrecks just inside the reef. The structure is typical north-coast Rottnest limestone: ledges and caves with sponges and colourful encrusting invertebrates on the walls and kelp on the reef top.
Fish life is good because the area lies within or beside the Kingston Sanctuary Zone. Expect leatherjackets, wrasse, bullseyes packed into the darker holes, and schools of bream over the reef, plus western rock lobster under ledges. The shallow depth gives long bottom times, and the caves are open enough that Open Water divers can enjoy them without true overhead penetration.
This is a good second dive for charter groups who have already done the wrecks, for divers wanting natural reef close to Thomson Bay when the south side is blown out, and for photographers who want light shafts through the swim-throughs. It is close to the Thomson Bay jetty and the main boating channel, so good surface discipline is essential. Because published information on the site is thin, go with someone who knows the reef or allow time to explore: the best caves are on the outer face rather than the reef top. A torch brings out the colour in the sponges and helps find lobster and cuttlefish tucked into the back of the overhangs. Stay clear of the yellow glass-bottom-boat mooring on the nearby wrecks when manoeuvring.
Research this site before booking Stored site notes may be historical. These questions highlight gaps without turning old instructions into a current dive plan.
Outer Transit Caves is recorded as Reef in Rottnest Island. The listed access is boat (day trip). 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.
- Other water users
- Ask about vessel activity, exclusion areas and the agreed surface arrangements.
- 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 Outer Transit Caves suitable for my certification?
The record lists 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 Outer Transit Caves 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
Leatherjackets, western king wrasse, bullseyes, buffalo bream, sweep, western rock lobster, sponges and colourful invertebrates
Location
Limestone swim-throughs and overhangs on the outer (seaward) edge of Transit Reef north of Thomson Bay, near the Macedon and Denton Holme.
Facilities nearby
Thomson Bay settlement facilities; public moorings on Transit Reef.
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
marinelife.org.aurottnestisland.comRecord updated 26 Sept 2026. Source claims are being reviewed.