Although salty, lake Kara-Kul is frozen and snow-covered until May but throughout the summer this huge lake is transformed into a beautiful, sky-blue lozenge that changes colour with depth. An attempt by META to declare it the world's highest navigable lake, beating Lake Titicaca, is not likely to succeed but a jetty erected a few years ago has enabled summer boat trips to the island and is the launching point for the Roof of the World Regatta.