Gentofte Lake (Gentofte Sø) is a narrow, calm lake at the centre of the municipality, surrounded by a nature reserve that provides an unexpected patch of green in the middle of an otherwise dense suburb. A footpath and cycle path circle the lake in about 45 minutes, passing through reed beds and stands of alder and willow. Waterfowl are abundant year-round; the lake is good for quiet birdwatching, particularly in spring.
The reserve around the lake includes Gentofte Kildeskov, a small ancient woodland on the western shore. The whole area is managed for nature rather than recreation — no swimming, no boating — but it functions well as a lunchtime escape for residents of the surrounding streets, and gives Gentofte a more rural centre than its suburban setting would suggest.
The lake is a short walk from Gentofte S-tog station, and can be combined with a visit to Kildeskovshallen (the public swimming centre on the eastern edge) for a full afternoon.