Sykes Reef lies north-east of Heron Island, about 45 minutes away by dive boat, and it is the Heron dive team's occasional special trip when the weather allows. Unlike Heron's gentle slopes and bommies, Sykes offers a proper drop-off with deep walls, and the clearer offshore water gives it a different feel from the reef around the island. Marine life writers highlight turtles, large fish and large gorgonian sea fans on the walls, and the site draws the reef sharks, pelagic schools and occasional manta rays that come with deeper water.

The upper reef is covered in healthy hard corals, and the combination of wall and reef top provides a multi-level dive with something at every depth. Trips to Sykes are usually paired with Bromfield Reef, which serves as a shallower second dive with coral gardens and morays. Because of the travel time, these trips take up most of a morning and are scheduled only when the sea is calm and there is enough interest.

Sykes Reef suits divers with Advanced certification or equivalent experience, since depth and open-water conditions are both greater than at Heron's home sites. Photographers should bring a wide-angle lens for the gorgonians and wall scenery. Divers staying at Heron for several days should let the dive centre know early if they are interested, as a special trip may depend on numbers and weather.

The long run also means the boat often passes open water where humpback whales travel between July and October, adding to the appeal of the trip in winter.

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. Sykes Reef is about 45 minutes north-east of Heron by dive boat, so it is visited only on special trips in calm weather. Private boats from Gladstone take 3 hours or more.

The Capricorn cays are exposed to the south-east trades (often 15-25 knots April-September), which make the Gladstone crossing rough and restrict diving to the lee (north-western) sides. The calmest windows are typically September-December and March-April. Northerlies in spring and summer reverse the sheltered sides.

Tidal currents run strongly around reef edges and channels on springs. Cyclone season November-April. Sykes Reef is further offshore than Heron and needs a calm day (winds under about 12-15 knots) for the 45-minute run; the drop-off is dived on the lee side.

Descend onto the reef top at 8-10 m and drop over the edge of the wall, following it at 18-25 m with the wall on one shoulder while scanning the blue. Turn at half air, ascend to the upper wall and reef top for the second half, and make the safety stop on the reef edge.

Heron Island Resort Dive Centre runs occasional special trips to Sykes Reef in calm weather, typically paired with nearby Bromfield Reef as a shallower second dive; occasional liveaboards.