Meet the site
The Tunnel is one of a trio of cave dives at the southern end of Black Rock, alongside The Arch and The Chimney. McFadyen describes a reef that drops from 9 m to a sandy bottom at 21 m, with a wall of rock coming down to the sand and a distinctive cutting in it. The Tunnel itself is quite long – perhaps 15–20 m – and does not end blind; it exits into a vertical hole that rises to the top of the reef at about 12 m. The Marine Life Network describes a 15 m cave with a collapsed roof, about 4 m high and 3 m wide, with sea fans and plenty of fish, at 22–24 m.
The rock here is igneous and covered in a striking purple coralline growth, with red, orange and yellow sponges, sea squirts and gorgonians. McFadyen describes eastern blue devilfish so tame they would take food from the hand – feeding is now discouraged – and wobbegongs and Port Jackson sharks often rest in the tunnel.
The dive has a satisfying shape: along a wall, through a tunnel and up a chimney-like exit onto the reef top, then back across the reef. The tunnel is roomy enough for most divers, with light at both ends, but it is still an overhead environment and suits Advanced divers with good buoyancy and a torch. Combined with The Chimney nearby, it makes a good two-dive day at the south end of Black Rock, only minutes from the ramp.
Research this site before booking Stored site notes may be historical. These questions highlight gaps without turning old instructions into a current dive plan.
The Tunnel (Black Rock) is recorded as Cave/Cavern in Batemans Bay. 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 The Tunnel (Black Rock) suitable for my certification?
The record lists Advanced 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 The Tunnel (Black Rock) 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
Eastern blue devilfish, wobbegongs, Port Jackson sharks, gorgonians, sea squirts, sponges, purple coralline algae, yellowtail, silver sweep, blue groper
Location
15–20 m long tunnel entered at 18 m that exits up a vertical hole to the reef top at 12 m, immediately south of Black Rock off Lilli Pilli, Batemans Bay.
Facilities nearby
Mosquito Bay (Lilli Pilli) and Hanging Rock boat ramps; air and nitrox at Beneath the Bay.
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.infomarinelife.org.aubeneaththebay.com.auspiritdiversdotcomdotau.wordpress.comRecord updated 26 Sept 2026. Source claims are being reviewed.