The Junction is a shallow Heron Reef site made up of scattered and broken bommies, with large plate, boulder and branching corals throughout. It is a busy reef, home to thousands of colourful fish, and has a resident Queensland grouper that guides point out to visiting divers. The site's special feature is the current.

Water movement concentrates plankton here, and manta rays come up to feed in the shallows, sometimes just one or two metres above divers' heads. When the mantas are feeding, the best approach is to stay low and still and let them loop around, rather than swimming up to them. Sharks also frequent the area.

The coral formations are impressive in their own right: large plates and boulders create shelter for reef fish, and the branching coral patches hold clouds of damsels and chromis. The broken nature of the bommies creates plenty of nooks for moray eels and other residents. The Junction suits Open Water divers who are comfortable with a moderate current and is particularly good for photographers hoping for manta images in shallow, well-lit water.

Manta activity varies with season and tide, being best in the cooler months. It was grouped with several other sites in the earlier database pass and now has its own row. Even when mantas are absent the dive is worthwhile for its coral formations and fish density, and the grouper is usually found around the larger bommies.

Turtles also move through the site regularly, and the shallow depth allows long, relaxed bottom times with plenty of light for photography.

Heron Island is 72 km north-east of Gladstone. Fly or drive to Gladstone, then take the Heron Islander ferry from the Gladstone Marina terminal (72 Bryan Jordan Drive; check-in from 7:45 am, departs 9:30 am on scheduled days, about 2 hours), or transfer by seaplane or helicopter. Dive gear is carried on the ferry in addition to baggage.

On the island, the dive centre sits beside the harbour; boats leave the jetty for three dives daily and most Heron Reef sites are 5-15 minutes away. The Junction is a short boat ride from the jetty.

Heron Reef sites are chosen on the day by wind and tide. The prevailing south-east trade winds (strongest April-September, often 15-25 knots) make the southern and south-eastern reef edge rough, so the sheltered northern and western sites are dived most. Northerly winds in spring and summer reverse this.

The tidal range is up to 3-4 m and currents run strongly around the reef edge and through Wistari Channel on springs; visibility is usually best on the incoming tide. Cyclone season is November-April; summer storms and plankton blooms can drop visibility to 10 m. Stingers are uncommon this far south but present in summer.

Currents at The Junction concentrate plankton and bring feeding mantas; it is best on a running tide.

Descend among the scattered bommies and move with the current, staying low among the coral. When mantas are feeding, hold position near the bottom and let them pass overhead rather than rising into their path. Finish in the shallows with an SMB.

Heron Island Resort Dive Centre is the only operator: three guided boat dives a day (about 9 am, 11 am and 3 pm) plus scheduled night dives, from the resort jetty; sites are rotated by tide and wind. Access requires a stay at Heron Island Resort (or the University of Queensland research station).