Hummock ice on Lake Peipus in Estonia

© Sven Zacek/Minden Picture

When ice imitates art. Lake Peipus, Estonia

Lake Peipus, on the border between Russia and Estonia, is the fifth-largest lake in Europe, dating back hundreds of millions of years to the Paleozoic Era. It is known for its sand dunes, which can 'sing' when the wind blows just right. In the winter, the frozen lake surface may feature ice hummocks, as seen in this image. The hummocks are caused by slow, uneven pressure in the ice pack.