One of the most famous beaches within walking distance of Lisbon is Massas Beach, also known as "Apple Beach", this name comes from the fact that once apples fell from trees at the source of the Ribeira de Colares river that flows along the south side of the city. The beach, then washed up on the beach, and one of the reasons for its popularity is the tram line that connects it to Sintra during the summer months, as well as the huge outdoor pool equipped with slides and diving boards and the children's pool.