Meet the site
Twin Bommies, also known as Twin Towers Reef, is the third of the outer Lonsdale reef's named bommie sites, lying between Lonsdale Arches and Lonsdale Bommies about a kilometre off Point Lonsdale in Bass Strait. The Scuba Doctor listing describes 'two substantial rock formations rising from an 18-metre seafloor', with 'abundant fish communities' and 'vibrant soft corals and sponges covering the bommies', and rates it Open Water at 12–18 m, ebb tide only.
The two towers stand close enough together to be dived as one site, each a steep-sided limestone stack 5–6 m high with undercut bases, ledges and splits, and the tidal flow through the entrance has coated them in the same soft corals, zoanthids and sponges as the Arches next door. The listing singles out Port Jackson sharks, which rest under the ledges at the base of the towers in numbers in the cooler months, and southern rock lobster in the cracks; the fish over and around the stacks are the outer-reef community of sweep, boarfish, magpie perch, old wives and wrasse, with cuttlefish in winter and seals passing from the Point Lonsdale haul-outs. It is, the listing says, an excellent photographic site, and the two towers give a diver a subject with sky behind it in a way that a flat reef cannot.
It is dived on the ebb on calm days, like the whole outer reef, and is usually combined with the Arches or the Bommies on an 'outside' charter day from Queenscliff or Portsea. For an Open Water diver it is a straightforward and memorable Bass Strait dive; the only requirements are a flat sea, the right tide and a boat that will pick up a DSMB downstream if the group drifts off the towers.
Research this site before booking Stored site notes may be historical. These questions highlight gaps without turning old instructions into a current dive plan.
Twin Bommies 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.
- 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 Twin Bommies 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 Twin Bommies 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
Port Jackson shark, southern rock lobster, soft corals, zoanthids, sponges, silver sweep, longsnout boarfish, magpie perch, old wife, bluethroat wrasse, giant cuttlefish, Australian fur seal
Location
Two large rock formations on the outer Lonsdale reef in Bass Strait about 1 km south of Point Lonsdale lighthouse, 83 m east-north-east of Lonsdale Arches and 142 m west of Lonsdale Bommies.
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.
