There are three lakes in the Vallee de Joux : the lac de Joux (around 6 miles (10 km) long), the lac Brenet and the lac Ter. The border with France is all along the north part of the valley.

About 5km southwest of Vallorbe, the sharp Dent de Vaulion rises to 1483m, standing guard over the secluded Vallée de Joux, a long thin valley sandwiched at 1000m between the Grand Risoud pine forest, which conceals it from France, and the parallel Mont Tendre range, which cuts it off from Lake Geneva. It's perfect summer walking country, with many routes along the valley floor beside the Lac de Joux, while the thickly wooded valley sides turn into cross-country skiing heaven in winter. The valley has its own, bracing microclimate, reminiscent of Alpine areas 400m higher in altitude: temperatures of -20°C on the valley floor are not unknown in winter, and precipitation tops 1800mm a year. High winds can also rip their way along the valley. It's no surprise that the first people to consider settling in the valley were ascetic monks: even by 1700 there were still just 173 inhabitants, plus 22 bears.

The Vallee de Joux is with Neuchatel, the birthplace of the Swiss horology and still home of the most famous swiss watch factories, like Audemars Piguet, Blancpain or Jaeger-LeCoultre.