nice day trip. if you want to enjoy the whole tour with 3 islands, you need to consider the tour starting at 8am, otherwise you can take any boat tour from 9h30 to 11h stopping in 2 islands, tianchi lake with a pool (see below picture) and huangshanjian which are nice themselves. Huangshanjian nice view after cable car. the boats are surprisingly comfortable with large sofa and tables , I took the upper deck but you need to pay extra 30rmb. in Tianchi lake you can enjoy eating some fruits and there are restaurants but most people would just take their own snacks.