Houtman Abrolhos
The Houtman Abrolhos is unusual in having a luxuriant and diverse living coral reef at such a high latitude. 194 species in 50 genera have been recorded there, all but two of which are tropical. This is a surprisingly high coral diversity, considering the high latitude of the reef, and the relatively low diversity of other biota. For a full list, see list of corals of the Houtman Abrolhos.
Pigeon Island (Houtman Abrolhos)
Pigeon Island is roughly triangular in shape, with a short side on the south west, and two long sides coming together at a point in the north east. The island is covered with infrastructure, with a high density of huts covering the entire island, right down to the water line; in total there are 54 camps, a school and a pub. There are also around 20 jetties, mainly along the northwest side, as this is the only direction from which the island may be approached by boat. The island is surrounded by reef to the south and east, but a passage known as Pigeon Island Anchorage runs along the northwest side.