Perhaps for people coming to Vienna, beaches are at the end of the list of attractions, but there are many beaches in the area, including the Strandbad Gansehaufel, in the 22nd District. This is an Austrian bathing beach formed of a little lake in the middle of the city. There are some areas of nude bathing on this beach, so be careful if you are easily abashed!
The Shafbergbad is perhaps the most famous beach in Vienna and its pool is large enough to hold many tourists, while the Strangbaeder Alte Donau is one of the oldest outdoor bathing arenas in Vienna. The area does not have pools, just manicured lawns that stretch along the side of the Danube. Relaxing on the grassy area is almost as good as having a sandy beach. The Ottakringerbad is also a green beach, located in the industrial district, this 'beach' has a pool and is a great place to relax for the day.
Simmering is one of the largest artificial pool areas in the city and there are small pools for children and larger ones with slopes for the adults. All of the pools have magical waves that give the impression of being near the sea.