Key Points:

The Chatham Islands' unique flora and fauna are a biologist's fascination and a golden goose to tourism. Some highlights of the islands' natural curiosities:

* The main island rises steeply from the sea in dramatic basaltic cliffs along its southern coast, to mostly flat pastoral land, long-denuded of the ancient tarahinau forest that used to clothe it.

In the north are spread white sand beaches and aquamarine waters. Te Whanga lagoon fills the Chatham Island torso, home to hundreds of black swans. You can find fossilised shark teeth at Blind Jim's Beach.

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* There are 18 bird species unique to the islands, once a clamorous rookery.

Chatham Islands black robin and taiko have both been rescued from the brink of extinction (the black robin got down to one breeding female, Old Blue, who's commemorated in a plaque hanging in the Chatham Airport lounge).

* Long-line fishing has come under fire for accidentally killing Chatham Islands' albatrosses and other seabirds. The bright yellow-billed albatross, which breeds only on a small island south of Chatham Island, is listed as critically endangered. Pressure by Forest and Bird has recently prodded the Government to dispatch observers and consider regulation of fishing methods that minimise seabird bycatch.

* Chatham Islands may be the only undisturbed remnant of the lost continent of Zealandia, a vast tract of the continental trust of which modern New Zealand is only the emergent tip. And the whole of Zealandia, including New Zealand, may have been under water until 23 million years ago. This theory, developed by geologists Hamish Campbell and Chuck Landis, rocks received wisdom that while New Zealand was once mostly submerged, some areas always remained above water, allowing the continuation of species from ancient mega-continent Gondwanaland, from which Zealandia split 83 million years ago.

If Campbell and Landis are right, it could explain why we have no indigenous mammals - they drowned.