The named islands are:
Ko Phi Phi Don, the largest and only populated island. You will not believe the amount of development this place has undergone, which is almost entirely restricted to the narrow sandbar separating two of the island's most prominent beaches. Marketed as a tropical island, the flurry of activity around the numerous supermarkets, restaurants, tattoo parlors and ATMs may just surprise you. Rest assured it delivers all the natural beauty it promises, amidst this rampant commercialization.
Ko Phi Phi Leh, a smaller island to the south, popularised when parts of the movie "The Beach" were filmed there. Uninhabited apart from bird nest harvesters and a few Maya Bay wardens; expect plenty of tourists during daylight hours, especially in Maya Bay, also known as 'the beach'.