Koh Khai Nok is a small island tucked away in Phang Nga Bay. It's only 30 minutes or so away from the east coast of Phuket but ask anyone on the island if they've been there and you will probably draw a blank stare. Still, a hidden gem is sometimes all the more precious for being so and when we discovered a half day tour was going there we leapt at the opportunity to try it out. It's a sunny morning at Royal Phuket Marina. Inside one of the side offices a large LCD TV shows previews of tours in Phang Nga Bay and the smell of fresh coffee wafts in the breeze. Souvenirs and candies are stacked high and above the cheerful din Cooper, our guide, informs us that it's time to move out. We traipse past multi-million dollar cruising yachts, powerful speedboats and an antique wooden rice barge to our double-engine speedboat.