Meet the site
The Adelaide River Mouth reef (AR4) is the easternmost of the four engineered reef complexes installed off the Top End in 2019, sitting in about 16 m of water off the mouth of the Adelaide River in Adam Bay, east of Gunn Point. The 2019 installation was part of an $8.3 million NT Government artificial reef project described at the time as the largest single installation of artificial reefs in the Southern Hemisphere, with a design life of well over 100 years. Each module is a purpose-built concrete structure about 5 m tall, 4 m square at the base and weighing about 24 tonnes, designed with openings and internal cells to provide shelter at several levels, and the modules are grouped into a reef complex rather than a single block.
The site was chosen for anglers: the Adelaide River is one of the Territory's great fish-producing rivers and the reef was placed to hold snapper, jewfish, cod and pelagics near its mouth. For divers, the setting is challenging. This is a turbid estuary-mouth environment with fine suspended sediment, strong tidal flows and, for much of the year, a plume of fresh water spilling from the river. Visibility is typically measured in a few metres at best.
On a rare clear late-dry-season neap, the modules would appear as tall grey towers on a mud and sand bottom, carrying sponges, hydroids and oysters rather than coral, with black jewfish, estuary cod and golden snapper around them and baitfish above. There are no published diver accounts and the site should be regarded as exploratory.
The Adelaide River is also one of the most crocodile-dense rivers in the world, and the risk around its mouth is higher than at any other artificial reef in the region.
Research this site before booking Stored site notes may be historical. These questions highlight gaps without turning old instructions into a current dive plan.
Adelaide River Mouth Engineered Reef is recorded as Artificial Reef in Darwin Offshore & Artificial Reefs. The listed access is boat (day trip). 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.
- Other water users
- Ask about vessel activity, exclusion areas and the agreed surface arrangements.
- Lines and obstructions
- Discuss any known entanglement concerns and the suitability of the planned area.
- 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 Adelaide River Mouth Engineered Reef 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 Adelaide River Mouth Engineered Reef 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
Black jewfish, estuary cod, golden snapper, barramundi (river mouth), threadfin salmon, queenfish, trevally, baitfish, sponges, hydroids (reported by anglers)
Location
Engineered concrete reef complex off the mouth of the Adelaide River in Adam Bay, east of Gunn Point (12°07.587'S 131°11.545'E).
Facilities nearby
Leaders Creek boat ramp (concrete ramp, limited facilities; fuel and supplies at Point Stuart/Corroboree area – check availability).
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
nt.gov.aufishingworld.com.aumarinelife.org.auRecord updated 26 Sept 2026. Source claims are being reviewed.
