Southern Coral Sea Reefs


The Coral Sea Islands Territory includes a most of the islands and reefs in the Coral Sea, to the east of the actual barrier reef.  This is pretty much the same as diving in the open sea, with the outstanding underwater visibility that goes with it. Remoteness ensures pristine reef and large fish that aren’t scared of divers. It’s also hard to beat the adventure of going to spots well off the beaten track. The large expanse of empty ocean off Mackay sees the outer reefs divided in to north western and southern sections, with different corals in each. The southern region corals tend to be smaller and less colourful that in the north and there are fewer deep drop-offs. Most of the diving is on gradually sloping bottom on pinnacles and coral heads interspersed with brilliant white sand. The lagoons rarely exceed 20 metres but it is possible to find some deep pinnacles. The area is covered in sea snakes and offers turtles, rays, sharks, and big schools of big fish.

The Coral Sea Islands are also bird sanctuaries and centuries of bird droppings led to the larger islands being mined for guano in the 1870s and 1880s. The lack of fresh water meant they were almost never settled.

Most of the southern reefs are never visited, except for the occasional private yacht and the occasional fishing charter. Diving parties will need to find a charter operator and band together to book the whole boat. September to January, provides the most reliable weather for Coral Sea access.


Southeasterly Group

Saumarez Reef

The Saumarez Reef is 330 km North East of Gladstone. They are one of the closer coral sea islands as they are only 85 km to the east of the Swain Reefs and 95 km to the southwest of the Frederick Reefs. This is the most visited area in the locality, which means it still isn’t visited often. Saumarez Reef contains three main reefs and numerous smaller reefs, all of which form a large crescent-shaped formation open to the northwest. It is about 27km by 14 km. There are two sand cays, North East Cay and South West Cay. There are many wrecks along its weather edge. The reef provides reasonable protection behind the reef.


North East Cay , Saumarez Reef


21°38′S., 153°46′E

The northernmost of the Saumarez Reefs offers a small sand cay 2.4m high. The cay is enclosed by a coral reef has an opening on the South Western side. A light, is shown from the Northern edge of the cay. A clear channel, about 2.1 km wide, lies between Northeast Cay and the next reef to the South.

The northern side of the reef tends to be the most dived with good coral gardens, gutters and caves. The caves are home to tawny nurse sharks, wobbegong, rays, crayfish and turtles. As with the region more broadly the bottom of the lagoon offers hundreds of coral pinnacles with good invertebrate life and these pinnacles are patrolled by lots of fish, reef sharks and sea snakes.


Wreck of SS “Francis Preston Blair”, South East Elbow Saumarez Reef

21°55′S., 153°35′E.

The South East Elbow is located about 36 km SSW of Northeast Cay, forms the South Eastern extremity of Saumarez Reefs. She is easily identified by the massive rusting hulk of a wartime freighter high and dry about 9.4 km North East of South east Elbow, on the eastern edge of the Saumarez Reef. On 15 July 1945 she came ashore during a cyclone. She was used on occasions as a target by the RAAF, which dropped practice and live bombs. The Francis Preston Blair was an American Liberty ship standard design,422.8 foot long and 7196 tons. She was built in 1943 by the Marin Ship Corporation Yard at Sausalito, San Francisco Bay. The wreck is high and dry and is worth a non-diving inspection. Be cautious as the wreck is now potentially dangerous as the rusted structure is becoming ever more fragile.

South West Cay

21°50′S., 153°30′E.

The cay is enclosed by a reef, 10.8 km NW of Southeast Elbow. It is the westernmost above-water part of the Saumarez Reefs, and is 2.4m high. There is a channel, 4 km wide between the cay and the reef SSE.


Frederick Reef

21°02′S., 154°23′E.

This 30km2 reef is 410 km northeast of Gladstone and 175 kilometres (109 mi) east from the Swains Reefs. Frederick Reef is a small atoll with a large rock called Ridge Rock at the southern end, a sand cay called Observatory Cay and a lighthouse at the northern end. The reefs forms a J shape to form a semi-enclosed lagoon, known as Anchorage Sound, with an opening on the North side. The reef is located near some deep water and drops sharply to over 2,500 metres on the western side. The reef offers good protection from SE Trade Winds.


Shipwreck of Royal Charlotte, Frederick Reef


In June 1825, the Royal Charlotte was transporting soldiers from Sydney to India. On 11 June, the ship ran onto Frederick Reef, ¾ mile south-west of the cay. The crew and soldiers moved to shore with water and provisions. Two lives were lost. A party took the longboat and travelled to Moreton Bay, arriving in July and raised the alarm. The survivors huddled for six weeks on the sand cay. They were finally rescued by the government brig Amity on 1 August 1825. In January 2012, researchers from the Australian National Maritime Museum found timber, rudder fittings, copper fastenings, an anchor chain, anchor and cannon. The wreck is a protected wreck and please do not interfere with it. There isn’t much to see other than the anchor, but the surrounding coral area around the anchor has nice reef and fish life.

Kenn Reef

6-10m lagoon

-21.267; 155.800Observatory Cay

Kenn Reef is a mostly submerged coral atoll over 280 nm north-east of Gladstone and140 km southeast from the Frederick Reefs. It is located on a submerged continental block, called the Kenn Plateau, which it shares with Bird and Cato Island. This volcanic block drifted from Australia around 64 to 52 million years ago. The reef is about 15 by 8 km and appears as either a backward facing “L“ or a boot. An islet in the Southeast part of the reef called Observatory Cay which is about l00m by 50m and 2m high above the high tide level with little vegetation.

Landing can be made On the SW side of the reef there is a conspicuous boulder. There is an exposed wreck of a long liner on the S side of the SW part of the reef. All the reefs dry at half-tide, and the sea breaks over all of them except for the South Western reef. The Northern reef encloses a shallow lagoon, which is entered on its Western side near the Southern end though a narrow channel but it offers a secure anchorage. The southern reef is the largest with three emergent sand cays on the SW part. The only permanent land, tiny Observatory Cay, about l00 m by 50 m and 2 m high has no vegetation. There is an excellent anchorage for all winds except northerlies

There are several old historic wrecks on the reef still to be discovered. The sailing vessel Bona Vista was wrecked on 18 March 1828 and it may be her anchor that is visible on the south-eastern reef when it dries.

The Canadian-built 484 ton wooden barque Jenny Lind was wrecked on 21 September 1850. The survivors built a boat out of the wreckage and sailed back to the mainland. The small 2 masted wooden schooner Alfred Vittery was lost on 9 March 1884. The Rodney a wooden ship of 877 ton went up on 7 January 1858.  Four Dutch vessels also went up on the reef, Hester (856 ton) on 21 April 1854; Doelwijk  (wooden barque of 725 tons) on 21 April 1854, a; Delta (wooden 902 tons) on 30 May 1854; Oliver van Noort (wooden barque of 607 tons) on 7 January 1858. Sportfishing is conducted around the island by Nomad Sportfishing, with clients reaching the island by seaplane from Hervey Bay to meet boats that are parked at the reef.

The wreck has plenty of good coral heads in the lagoon interspered with brilliant white sand. South Eastern Reef offers a good Anchorage in 6 metres, (21°15 066’ S – 155°46.327’ E) with good diving and lots of seabirds, common noddies, brown boobies and frigate birds.


Wreck Reefs

These reefs are located 450 km East of Gladstone, and 250 km east of the Swain Reefs complex. They form a narrow chain of reefs with small cays that extends for around 25 km by 5 km in a west to east direction. It consists of patches of coral reef separated by navigable channels and is the home of seabirds and turtles. The sea always breaks over the cays. The reef is named after the colonial sloops Porpoise and Cato, wrecked here in 1803. The wrecks are protected as a historic wreck site. The islets along the reef include Bird Islet, West Islet and Porpoise Cay.



Bird Islet

-22.167; 155.467(Bird Islet)

The islet is a mound measuring some 500m by 250m and 6m high with a bare centre surrounded by a ring of herbage. It is an important seabird roost.

In 1803 the explorer Matthew Flinders left Port Jackson on his way home to England in H.M.S. Porpoise in company with the Cato and Bridgewater. The Porpoise and Cato hit Bird Islet. Three young lads were drowned. There the shipwrecked men found part of the stern-post of an even earlier wreck, a ship of about 400 tons. Flinders and thirteen others including Captain Parker, rowed back to Sydney in the ship’s cutter. Governor King dispatched ships and rescued the shipwrecked crews. In 1965 after extensive research and only fifteen minutes of actual diving Ben Cropp & Jiri Hrbac found the wreck sites.

Another larger wreck was theAmerican whaler Lion, wrecked on 4 December 1856. They took to the boats and arrived safely at Maryborough on the mainland.

On 27 October 1862, an exclusive guano concession was granted to the Anglo-Australian Guano Company. They were active on Bird Islet, losing five ships at Bird Islet between 1861 and 1882. About 12 000 tons, or nearly 2 metres of soil was probably removed by teams of 20 to 30 men and taken to Tasmania.

Most of the wreckage and many of the coral pinnacles in the lagoon are in snorkelling depths.

Less common in this region, the island also offers a deep drop-off on the northern side of Bird Island dropping from 10-200 metres. The wall offers excellent corals, gorgonia, sea whips, sponges and smaller invertebrates. The wall is patrolled by sharks, school fish and turtles.


Porpoise Cay

Lagoon 2-12m

This cay is 275m long, 90m across and 3m high. It has a few low plants and lies 11 km west of Bird Islet in the centre of a shallow lagoon surrounded by a reef. The reef partially uncovers at low tide. The area can be accessed on the north side where there is a 100 metre wide sand patch and partial shelter from the trade winds. The bottom is coarse sand with coral heads on all sides. There is good bird life with .white masked boobies, common noddies and brown boobies. Apart from the all too common plastic flotsam, there are pieces of coal and metal from the old wrecks still visible among the rocks.

Most of the wreckage and many of the coral pinnacles in the lagoon are in snorkelling depths.


Cato Reef,

-23.250; 155.533 (Cato Island),

2-17m lagoon

The reef lies 62 nautical miles south of Porpoise Islet. Cato Reef and its lagoon only cover 5 km2; but Cato Bank is a large area of shallow 21km by 13 km. Cato Island lies in the western part of the lagoon and is an oval shape a mound of coral debris and grit of 650m by 300 metres. It has good bird life. It is 6 m high and houses an automatic weather station on the north-east end of the island. The lagoon contains numerous coral heads, turtles and big fish.

Close to the Southeast corner of Cato bank is Hutchison Rock, with 1 m depth over it. The reef lies 375 km east of Gladstone and 115km south of Bird Islet. The best entrance to the lagoon is located 350 meters north of the eastern end of Cato Island; it has a conspicuous rock at half tide on its eastern side.

Danger Patch lies near the outer end of the eastern ledge of Cato Bank. A tidal race is found between the eastern end of Cato Reef and Danger Patch. Cato Reef has always been a hazard to shipping and has seen in 1853 the wreck of the German sailing ship Dockenhuden. The 346 ton barque Thomas King also went up in 1852 while on her way to China.