Cascais is situated on the western edge of the Tejo estuary, between the Sintra mountains and the Atlantic Ocean; the territory occupied by the municipality is limited in the north by the municipality of Sintra, south and west by the ocean, and east by the municipality of Oeiras.
Today, there is a large yacht harbour and several small sand beaches in and around town. Cascais is easily reached from Lisbon by car, (A5 Lisboa-Cascais highway, or the scenic "marginal" road), or by frequent inexpensive commuter trains. It has the ruins of a castle, an art and sea museum, as well as parks and the charming cobbled streets of the historic centre. The town has many hotels and tourist apartments as well as many good restaurants of varying cost. It is a fine base to use for those visiting Lisbon and its environs who prefer to stay outside of the city yet in an equally urban and sophisticated environment.
Cascais is surrounded by popular beaches, such as Guincho Beach to the west, and the lush Sintra mountains to the north. Some of its shoreline is cliffy, attracting tourists for its seascapes and other natural sights such as the Boca do Inferno. It is also becoming a popular golf destination, with over 10 golf courses nearby. Surfing, sailing, windsurfing, and kitesurfing are also popular in the region around Cascais due to favourable weather, wind, and sea conditions. In 2007, Cascais was the official host of the ISAF World Championship in sailing for dinghies and racing yachts.