The polygon ponds in the flat sediment tundra of the delta are formed by ice-rings, which form against each other ring-formed walls. - The Lena delta is one of the largest still pristine river deltas in the world. Its many naturally meandering arms form a magnificent tree-like shape. On August 12, 1996, the Russian Republic of Sakha (Yakutia) significantly expanded the Lena Delta state nature reserve. At 14,330 square kilometres, the Lena Delta reserve ("Zapovednik") was already one of the largest and most important nature reserves in the Arctic. With its new size of 61,320 square kilometres, the expanded Lena Delta Reserve is now the largest protected area in Russia and one of the largest on earth. It is, however, only a small part of Sakha’s “Gift to the Earth”. Sakha, a republic approximately the size of Western Europe, decided in 1994 to designate at least 20% of its territory as a nature reserve.