With its entrance off a narrow hutong near subway lines 4 and 6, the public pool at Ping'anli is an excellent choice for notching up some laps on the west side of town. It's said that a few decades ago the pool used to be for military use only, later opening to civilians. Facilities are clean enough, with ample hot water for the showers. Do bring your own padlock for storing your things while you swim as none are provided. Afternoons and summer hours can be busy with young kids, but evening hours are generally not too crowded.
Don't go here looking for a pre-work swim as the pool is filled with classes and private lessons in the morning, and it doesn't open until midday for public use and free swims. But what it lacks in hours, it makes up for in its proportions and cleanliness. The 50-metre, regulation-sized pool boasts eight lanes (with options in both shallow and deep water), which are perfect for the serious swimmer.