Nai Harn is South of Kata and north of Promthep Cape, A quiet little spot at the southern end of Phuket, due to the under development. This is down to the Samnak Song Nai Harn monastery, in the middle of the beach.
This has stopped excessive development and is the reason that the beach is less crowded than other areas in the southern part of the island. Nai Harn is very quiet and there's little in terms of dining, and entertainment on the beach itself.
Great for swimming from November to April, however care should be take in the low season (May-October) when there can be strong undertows on occasion.
The few accommodation options that are near the beach and are mostly up-market and new developments and private villas.
This guide has some Nai Harn Beach Villas for rent and also real estate sales of Nai Harn Villas.