Meet the site
The East Extension, known as EEX, is one of the most significant cave discoveries in Mount Gambier in decades. In 2019 divers pushing beyond the main chamber rockpile of Engelbrecht East found a major new network of submerged passage under the city, and the CDAA now lists it as a separate Advanced Cave site. It offers more than 400 m of submerged tunnel with a maximum depth of about 22 m – considerably deeper and longer than the shallow East passage that leads to it.
It is a sidemount-only site, and the named features explain why. The Rabbit Hole is a tight restriction that the CDAA warns poses a drowning hazard if attempted without preparation and correct gear configuration, and steel cylinders larger than 7 L are banned there. The Caterpillar tunnel is so silt-sensitive that even minimal disturbance reduces visibility to zero. Seasonal water-level fluctuations change the clearances. Cave-rated divers who dive the East passage must stop at the rockpile – they are not permitted into the Extension.
Because of those risks, EEX is managed tightly: a maximum of four divers per timeslot, two timeslots a day, a minimum of two per booking, sign-in with site staff, and a ban on all training. For experienced Advanced Cave sidemount divers it is a rare chance to dive relatively new passage in a city-centre cave; for everyone else it is a reminder that the easy East passage is only the doorway. Because EEX is reached through the East passage, every dive is effectively two dives in one: a shallow silty approach, then a committed sidemount push, so plan gas and time around the full distance from the lake.
Research this site before booking Stored site notes may be historical. These questions highlight gaps without turning old instructions into a current dive plan.
Engelbrecht Cave – East Extension is recorded as Cave/Cavern in Mount Gambier Sinkholes & Caves. The listed access is shore. 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.
- Planned depth
- Confirm the intended route and training requirements; the recorded maximum is not a target.
- 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 Engelbrecht Cave – East Extension suitable for my certification?
The record lists Cave/Cavern certification. 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 Engelbrecht Cave – East Extension 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
Essentially none
Location
Over 400 m of sidemount-only submerged tunnel beyond the main chamber rockpile of Engelbrecht East, discovered as part of the 2019 new cave network under Mount Gambier; max 22 m.
Facilities nearby
Café, toilets, viewing platforms at Engelbrecht Cave; fills in Mount Gambier.
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
cavedivers.com.auen.wikipedia.orgRecord updated 26 Sept 2026. Source claims are being reviewed.