Meet the site
Trimix Corner is the starting point for the deepest dive in Victoria. The Scuba Doctor listing gives the site a range of 30–103 m and describes it as the corner of the Nepean-side wall from which divers 'descend along the wall seeking the deepest spot' – Entrance Deep, 'Victoria's deepest known dive location at 103 metres, the bottom of the ancient River Yarra just inside the Port Phillip Heads in the main shipping channel'. It lies 28 m from the Nepean Wall mark; the recreational Nepean Wall dive and this one begin within a boat-length of each other and have nothing else in common.
The wall below 40 m is, in the listing's words, 'very black, barren and rocky, with incredibly treacherous currents'. The encrusting life of the upper terraces gives way to bare rock and rubble in the dark of the channel floor, and the interest of the dive is the place itself – the deepest point of the drowned river that carved The Rip, in the middle of the shipping lane through which the port's traffic passes. Sevengill sharks are the most likely large animals.
Everything about the dive is dictated by the tide. The slack is very short at the entrance, and the ascent must be made up the shot line for as long as possible, because once the ebb begins it 'will quickly push you back over Rip Bank with a minimum depth of 20 metres' – that is, a team on decompression will be carried out through the Heads, and the recovery happens outside in Bass Strait. That requires a dedicated surface team, agreement with Lonsdale VTS, calm seas and divers whose deco can be completed drifting in the open. It is a dive for a handful of the state's most experienced trimix divers, made rarely, and it is included here because it is the extreme end of the Port Phillip Heads system rather than because anyone should plan to do it.
Research this site before booking Stored site notes may be historical. These questions highlight gaps without turning old instructions into a current dive plan.
Trimix Corner / Entrance Deep is recorded as Wall 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.
- Current and timing
- Ask how the operator assesses the current window for the actual route. Historical tide notes are not a departure instruction.
- Planned depth
- Confirm the intended route and training requirements; the recorded maximum is not a target.
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 Trimix Corner / Entrance Deep suitable for my certification?
The record lists Technical (decompression). 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 Trimix Corner / Entrance Deep 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
Sparse below 40 m – bare rock and rubble; sevengill sharks; the upper wall shares Nepean Wall's soft corals, sponges and blue devils
Location
The corner of the Nepean-side wall 28 m north-north-west of the Nepean Wall mark, from which technical divers descend to Entrance Deep – the 103 m bottom of the ancient Yarra channel in the main shipping lane just inside Port Phillip Heads.
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.auscubadoctor.com.auRecord updated 26 Sept 2026. Source claims are being reviewed.
