I went rafting in the Underground Grand Canyon. I bought tickets from Little Flying Dragon for 30 yuan per person and waited in line for over half an hour to get in. The temperature inside the cave was comfortable, and the underground scenery was truly unique. The line for the rafting was long, so I skipped it. It was fun watching others rafting.
The Firefly Water Cave is not recommended this season, as it requires a long walk through a greenhouse, which was too hot. Then there's the 1.5-kilometer walk to the cave, where I opted for rafting for 50 yuan per person. To see the fireflies, you take a boat into the pitch-black cave, where you can see faint pinpricks of light. It takes about three minutes. The sightseeing bus is 10 yuan each way, which is actually a short distance, but I didn't want to walk in the heat. There are souvenirs and local specialties for sale at the exit, and the prices are very reasonable. A bag of taro costs 5 yuan, and three pounds of yellow peaches cost 10 yuan. The two scenic spots are not far apart, and there's a shuttle bus, but I drove myself.