Along a bend of the Seine, the National Forest of Saint-Germain-en-Laye extends across 8,648 acres, and is the second-largest forest in Yvelines, following the Rambouillet forest. It's a setting for lovely walks with family or friends, with many hiking paths winding between its sessile oaks, beeches, hornwoods, and other pines. There are 2-kilometre paths for children, and 18-kilometre paths for seasoned hikers. More athletic visitors can take the Sylvestre path, which features exercise equipment. The Saint-Germain-en-Laye forest can also be visited on bicycle or on horseback.

During their walks in the Saint-Germain-en-Laye forest, visitors can discover the royal history of this place. It was very popular among Henri IV and Louis XIII, who went fox hunting here. Louis XIV built the Grande Terrasse here, which towers over the Seine valley and is nearly two kilometres long, as well as the Château du Val. They currently make up one of the historic sites in this forest, along with the Pavillon de la Muette and the Couvent des Loges.