Popular Korean bathhouse New Star has outdoor pools at two of their locations: the classic one in Hongqiao and the new one in Pudong. The outdoor pools are for anyone to use from 10am to 8pm, you just show up and pay the 118rmb ticket (or they've got a discount on Dianping), which gets you into the baths, the saunas and all the other cool shit. Of course, it's popular at weekends, but the sanitation level is high. Swim caps are required. No health check necessary. For other New Star listings click here. Note: New Star kicks foreigners out after midnight.