The outdoor swimming pool at Casa de Campo.
A favourite with the madrileños and great for kids. It's located in the massive green space of Casa de Campo. It's also very cheap costing 4,35€ for adults, 3,50€ for young people and 2,65€ for kids under 14. To get there, take line 10 to Lago.
If you fancy a bit of indulgence, it's worth buying a pass for one of the hotels with a rooftop pool. We recently visited the rooftop pools at the Hotel Emperador ( Gran Vía 53) and the Roomate Oscar ( Plaza Vázquez de Mella 12), and both were fantastic relaxing places with superb city views. Both have air conditioning and offer bar and restaurant services. What more could you need?
The pool at the Hotel Emperador is really something!
Kids will love it here! Aquopolis is a water park located in San Fernando, a few kilometres from Madrid. There are plenty of waterslides, swimming pools and water mazes as well as tamer attractions for the very small. Admission costs 19,95€ for adults and 14,95€, although if you buy online you can save a few euros. You can also buy combined tickets which allow entry to other attractions such as the Madrid Zoo or Faunia etc... To get there, you can take the cercanías local train to San Fernando and then bus 1, or one of a number of buses which leave Madrid's Avenida de America bus terminal. See website.
Head to the beach
Madrid is about a far away as you can get in Spain from the coast, but it is still possible to visit the beach. Just recently the city hall opened its 'River Project', a massive construction project which has transformed the area around the Manzanares river in the south-west of the city, and one of the things they have created is a beach. The beach will open officially at the end of July and deckchairs will be available for hire for just 1€ a day!
Leave the city!
When Madrid is scorching hot, up in the nearby moutains the temperature is always much more refreshing. Manzanres el Real is a village with a restored castle situated next to a lake (you can take the bus 724 there from Plaza Castilla, every 30mins), or if you have access to a car you could explore the towns of Lozoya, Rascafria, Pinilla del Valle which are near to lakes for bathing.
Failing this, you can always make yourself a nice bowl of homemade gazpacho or salmorejo, delicious on those scorching Madrid summer days and much better than the stuff you buy in the supermarket!