Kenn Reefs - General

General

Kenn Reef is a remotely situated reef in the south eastern waters of the Coral Sea, it lies approximately 100 km northeast from Bird Islet part of the Wreck Reefs and 140 km southeast from the Frederick Reefs; the Bellona Reefs of New Caledonia are located a further 277 km to the east, with the Australian mainland being located over 500 km to the southwest.

Kenn Reef is part of a submerged continental block, called the Kenn Plateau. The Kenn Plateau lies off the north eastern Australian coast and is a region characterised by a series of prominent, bathymetric troughs and marginal plateaux. And is submerged by 1000 m to over 3000 m of water. The Kenn Plateau, covers around 100,000 km², an area larger than the Tasmanian landmass.

Various islands and reefs, whose origin is thought to be related to the Tasmantid Chain of volcanic seamounts, lie along the western margin of the Kenn Plateau and include the well known Kenn Reef and Bird and Cato Island.

The Kenn Plateau is thought to have formed as a sliver of continental crust, resulting from the rifting and seafloor spreading that occurred between 95 and 52 million years ago, along the eastern Australian margin forming the Tasman and Coral Sea basins

The Kenn Reef areas consists of four main reefs which cover an area of approximately 40 km² looking like a backward facing L-shaped structure (or boot) of 15 km in length, with a maximum width of 8 km along the southern edge.

The three southerly reefs (the toe, foot & ankle and shin of the boot) lie upon a common shelf from which the northern (leg) reef is separated from by a deep channel. The smallest unit and most westerly of this chain (the toe), contains a conspicuous boulder, 1.8m high, on its NE side, which from a distance appears as part of a wreck. Landing can be made on the SW side of the reef. An exposed wreck of a long liner lies on the S side of the reef.

The ankle or the South Eastern reef is the largest reef and with two sand cays on the SW part of the reef the only permanently emergent land the tiny Observatory Cay 21°16′S 155°48′E / 21.267°S 155.800°E / -21.267; 155.800 (Observatory Cay - Kenn Reefs), which is about l00m by 50m and 2m high with a little vegetation. The western side of the ankle of the reef complex forms a bay All the reefs dry at half-tide, and the sea breaks over all of them except for the South Western reef.

The Northern (or leg) reef encloses a shallow lagoon, which is entered on its Western side near the Southern end.