I will be at a conference at the Tsinghua Sanya International Mathematics Forum December 17–21. I don't know the weather well, but I've been keeping an eye on the forecast, and it looks like it's lovely right now, so hopefully it won't be too cold in December. My previous trip to China (well, Hong Kong) spoiled me with all the excellent hiking. I don't expect nearly the same level of hikeability on an island, but maybe there's something.
Is there any hiking or other outdoor activity that can be done:
alone,
without much equipment, and
hopefully without needing a car in the area?