This protected area at the end of Lac Léman is swimmable year round (reaching 25C in summer and plummeting to 3C in winter). It is a very popular spot with many special events: the Christmas Cup, a fun 120m swim in December with 4,000 people (and extensive support from the police and lake- safety teams); live classical music at dawn in summer; plenty of picnic space; and New Year dips.
It has a beautiful basic restaurant (around SFr15 (about £13) for the menu of the day) with log-fired heaters and an outdoor terrace, a sauna and changing and shower facilities. Watch the lake cruisers sail past, drift past the lighthouse, dive to see the giant catfish and swim alongside swans and waterbirds. The water quality is impeccable (hey, it’s Switzerland), but you need to shower afterwards at the peak of summer, as duck fleas are possible. Website; Directions
— Peter Ransome, diplomat, Nyon, Switzerland