Pasir Panjang is the best beach in Kai Kecil island in Indonesia. However, almost each village in the west of the island has a nice beach. Unfortunately, there is not always a good hotel. Shore and seabed: sand. 
High season on the island is the period from June to August, when it is relatively cool and no much rains. The worst time to visit the island is the rainy season from November to April with the peak of rains in December-January.