Hainan visa-free entry is island-only
Sanya is a visa-free entry port for 59 countries, up to 30 days via Sanya or Haikou — but the waiver covers Hainan only. You cannot fly on to mainland China on it without a separate visa, so treat the island as the trip, not the gateway.
November to April is the season
The dry months bring calm seas and comfortable heat. July to September is hot, humid and the stretch when typhoons come through, and a storm can close the ferries and the island day trips for a day or two.
Pick a bay, not the centre
Sanya has no real downtown to speak of — it is a string of bays. Yalong Bay has the calmest swimming, Dadonghai is central and walkable, Sanya Bay (the Coconut Dream Corridor) has the best-value sunset stays, and Haitang Bay is where the luxury resorts and the Wuzhizhou ferry sit.
The beaches are public
Every beach in Sanya is open to the public and free to walk. The resort clubs charge for loungers, umbrellas and water toys, not for the sand — so you can bring a towel and sit anywhere the hotels have not roped off.