Is it cold to go to Hainan seaside at night?

You don't need to take any shawl, because it's hot during the day and cold at night, because you'll know when you arrive. It doesn't matter what slippers you'd better wear. When you get there, you can tow your shoes away. The sand on the beach is soft and won't hurt. When you leave, rush into the sea and put on your shoes. Diving depends on whether you come by yourself, join a group or have friends here. It can be much cheaper if you know the divers here. The least expensive and cheapest seems to be 180, depending on where you want to dive. Besides, Hainan is really hot, that's all. Have a nice trip.