Loh Dalum Bay is probably the best the best beach for swimming on Phi Phi, if not Thailand. The bay is extremely shallow, and you can easily walk 100 meters (or yards) from shore, and still be only thigh deep. Most of the hotels and resorts here are part of the village that covers the narrow spit of sand that separates Loh Dalum and Tonsai bays, so the will have equal access to all the shops and restaurants of the village.