Meet the site
Deep Pinnacles is the deeper continuation of the outer Lonsdale reef, a field of 'scattered reef and rock bommies rising out of the sandy sea bed' at 16–25 m south-west of Point Lonsdale, in line with the Lonsdale Arches reef and 250 m from Castle Rock. The Scuba Doctor listing (GPS verified) describes the soft calcarenite as 'eroded into lots of little swim-throughs, valleys and overhangs, all topped off with a light scattering of kelp', and the colour as 'yellow zoanthids and awesome colour'. Golden Arch, a natural arch to 23 m, is 137 m to the west on the same line.
The bommies stand a few metres proud of the sand, separated by valleys and linked by short tunnels that the current has bored through the soft rock; the undersides of every overhang are yellow with zoanthids and studded with sponges and jewel anemones, and the kelp on top is thin because of the depth. The listing's fauna – crayfish, blue devils, abalone 'and much more' – is that of the whole outer reef, with the addition of the animals that prefer deeper water: bigger schools of sweep and boarfish, Port Jackson sharks under the ledges, cuttlefish in season, and the occasional sevengill shark or seal passing over the sand.
Because it lies a little further from the entrance than the Arches and Castle Rock the tide is gentler and the listing rates it diveable on any tide as well as at slack; the constraint is Bass Strait swell, and the boat ride out through the Heads. At 16–25 m it is an Advanced site and a natural step up from Castle Rock for divers who have done the shallower outer reef; it is dived by charters on calm 'outside' days and by club boats, and it rewards a torch and a camera.
Research this site before booking Stored site notes may be historical. These questions highlight gaps without turning old instructions into a current dive plan.
Deep Pinnacles is recorded as Pinnacle/Bommie in Port Phillip Heads. 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.
- Planned depth
- Confirm the intended route and training requirements; the recorded maximum is not a target.
- Water movement
- Ask how swell and local exposure affect the proposed entry, exit and route.
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 Deep Pinnacles 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 Deep Pinnacles 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
Yellow zoanthids, sponges, jewel anemones, southern rock lobster, southern blue devil, abalone, silver sweep, longsnout boarfish, Port Jackson shark, giant cuttlefish, Australian fur seal, kelp (sparse)
Location
Scattered reef and bommies on the sand just outside the Heads on the Point Lonsdale side, about 1.8 km south-west of the lighthouse in line with the Lonsdale Arches reef; 250 m west-north-west of Castle Rock and 137 m east of Golden Arch.
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
scubadoctor.com.auscubadoctor.com.auRecord updated 26 Sept 2026. Source claims are being reviewed.
