Four Mile Reef is a low patch of reef on sand roughly 3 nautical miles off the coast between Bargara and Elliott Heads. It is a modest site in terms of topography – the reef rises only a few metres above a sandy seafloor at about 13 m – but it has two things going for it. First, it usually has better visibility than the coastal shore dives, because it sits outside most of the runoff that clouds the inshore water after rain. Second, it lies on the path of the manta rays that move along the Bundaberg coast in winter, and marinelife.org.au lists mantas among its regular visitors.

Resident life is typical of the Bundaberg offshore reefs: cod, bannerfish, angelfish and butterflyfish around the reef, turtles resting and feeding, and rays on the surrounding sand. The low profile means the fish tend to stay close to the reef, so a slow circuit is more productive than swimming away across the sand. Sponges and soft corals cover much of the rock.

The site is not dived commercially on a regular basis and there is little published detail beyond the marinelife.org.au summary and the GPS mark. It is best treated as a local boat dive for divers with their own vessel, or an alternative on a calm day for a club charter. It is shallow enough for Open Water divers and gives long bottom times, and a winter visit on a clear day with a manta pass would be memorable. On an average day it is a pleasant, easy reef dive rather than a destination in itself.

Pair it with Hoffman's or Barolin Rocks for a shore dive in the afternoon, or with Cochrane Artificial Reef if you want a second boat dive with more structure.

Launch at Burnett Heads boat ramp (15 km north-east of Bundaberg) or, for a shorter run to this southern mark, at the Elliott Heads boat ramp at the mouth of the Elliott River (about 20 km south-east of Bundaberg via Elliott Heads Road). The site is about 3 nm offshore; marinelife.org.au publishes the mark as 24°59.430'S 152°33.220'E. Allow 20-30 minutes from Burnett Heads in a small boat, less from Elliott Heads (the Elliott River bar is shallow and best crossed on the top half of the tide).

Anchor in sand beside the reef; there are no moorings.

Four Mile Reef lies in open water with no shelter, so it needs a light-wind day – ideally under 12-15 knots – and small seas for a small boat. South-east trades above 15 knots or any north-easterly sea breeze build a short, uncomfortable chop. Visibility is often better than on the coast because it sits beyond the reach of most river plumes, but heavy summer rain can still push dirty water out this far.

The Elliott River bar is shallow and dangerous on a low tide with swell. Winter mornings with westerly land breezes are the best window, and coincide with the manta season.

Anchor off the reef edge, descend to the sand at about 13 m and swim a loop around the low reef, working slowly because the reef stands only a few metres proud of the sand. Keep an eye up into the water column for mantas in winter. Return to the anchor line with a third of your gas and complete a safety stop on the line.

Bundaberg Aqua Scuba – occasional boat dives from Burnett Heads when weather allows (more often to Cochrane Artificial Reef); otherwise private boat or club charter from the Burnett Heads ramp only.