When the weather's still hot take advantage of this great day trip. You start on a wagon pulled by a buffalo to the dock. From there you take a raft down the river on the side of which local food is available. By the end they've got hot air balloons taking riders to great views, kayaks for the paddle hardy, and cold beer on the riverside. Not a wasted day at all.
The rafting is organised through the Hangzhou Tourist Office at Dragon Stadium (黄龙旅游集散中心). Go there to book and buy your tickets at least one day in advance. It takes 40 minutes to get there. Coaches leave in the morning and return before 5pm. 90RMB per person - that includes the return bus trip, the 60RMB entrance fee and a guide.