People ride mountain bikes on a sunny winter afternoon on the frozen Lac de Joux in Le Pont February 12, 2012. With a surface area of 9,5 square kilometres (3,33 square miles) the lake is the largest natural ice rink in Switzerland. With a thickness of up to 30 cm (11,8 inches) it is due to support the estimated 15,000 people that will enjoy it over the weekend. (via Photo from Reuters Pictures)