One of the highlights of this trip is the swim through an underwater tunnel that opens out into Emerald Bay. It is truly stunning. With a small beach and lush green surrounds, not to mention the soaring limestone cliffs engulfing you. Make sure you take a waterproof bag with you so you can take your camera in.
There are two ways you can explore these islands, one is on a larger boat with lots of other people or you can opt for a more personal trip on a longtail boat, whatever your choice, you can book this trip at any local travel agent or through your accommodation.