Tucked away in the north east of the Indonesian archipelago is Irian Jaya, the western half of New Guinea. The most westerly end is known as Raja Empat and this isolated part of the planet is gaining a degree of notoriety: most people never heard of it and almost no-one lives there. The only visitors are divers.

It all started in 2001 when Australian scientist, Dr. Gerald Allen, took an expedition to the Raja Empat (Four Kings) islands. In a single one-hour dive he spotted 281 different species of fish and registered 950 species overall. His colleagues recorded 450 species of coral (more than half the world's total with at least seven new to science) and nearly 700 species of mollusc.

The news soon got out and dive liveaboards started heading north to see what was there. And there's plenty, a huge variety of creatures on the reefs and walls. Schooling fish, soft and hard corals, crustaceans, cephalopods.... plus the occasional wreck. Bigger pelagic fish are not so abundant but we were visited by mantas on our last day.

You'd be pretty smart to spot fish in the numbers the scientists did, although on one dive, we tagged eleven different fish on a one metre outcrop before giving up. It was all too confusing. Small critters are everywhere - we saw nudibranchs we'd never seen and more pygmy seahorses than ever before.

The landscapes around Raja Empat are spectacular, limestone pinnacles ringed by turquoise lagoons with birds everywhere, huge fruit bats and butterflies flitting past the boat.