Meet the site
Flinders Islet is the island Wollongong locals call Toothbrush Island because of its long thin handle and lumpy 'brush' end, and it is one of the five low islands of the Five Islands Nature Reserve that shelter the approaches to Port Kembla. Its northern end is cut by a series of gutters that run west-south-west to east-north-east across the reef, giving one of the more interesting shallow boat dives in the Wollongong area.
The dive starts in a large gutter about three metres wide with a rocky, kelp-covered bottom around 12–14 m. Swimming east you pass into a sequence of narrower channels – roughly two metres at the mouth and closing to barely a metre at one point – with walls 10–16 m tall that are dotted with small sponges and encrusting life. The gutters lead to the cave, which undercuts the island at about 10 m. The entrance is a few metres high and opens into a chamber that runs back under the island, with a long arm branching right for another 15–20 m. Small gorgonians grow inside, red rock cods sit in the gloom, and the floor is fine silt, so good finning technique matters.
Outside, the kelp-lined gutter floors are good places to look for weedy sea dragons, and striped seapike patrol the channels. Visibility around the islands is frequently better than on the mainland beaches. The site is shallow enough for Open Water divers who are comfortable in a confined space and with a torch, and the gutters offer interest even if the cave is skipped. It combines well with a deeper dive at Toothpaste on the southern end of the same island, or with Pig Island further out.
Research this site before booking Stored site notes may be historical. These questions highlight gaps without turning old instructions into a current dive plan.
Toothbrush Island Cave is recorded as Cave/Cavern in Wollongong & Kiama. The listed access is boat. 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 Toothbrush Island Cave 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 Toothbrush Island Cave 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
Red rock cod, striped seapike, weedy sea dragons, bullseyes, one-spot pullers, leatherjackets, blue groper, small gorgonians, sponges, kelp
Location
Gutters and a sea cave at the northern end of Flinders Islet ('Toothbrush Island') in the Five Islands Nature Reserve, a few kilometres off Wollongong city centre.
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
michaelmcfadyenscuba.infoRecord updated 26 Sept 2026. Source claims are being reviewed.
