Severnaya Zemlya any traces of land to the north of the wide strait between the Kara Sea and the Laptev Sea that they navigated. The archipelago was not put on the map until the 1913–1915 Arctic Ocean Hydrographic Expedition of icebreakers "Taimyr" and "Vaigach". The chief organiser and first captain of the Vaygach was officer Aleksandr Vasiliyevich Kolchak of the Imperial Russian Navy. The expedition was privately financed and was launched in 1910, being led by Boris Vilkitsky on behalf of the Russian Hydrographic Service. This venture accomplished its goal of exploring the uncharted areas of the continental side of the Northern
Severnaya Zemlya as Arctic lemming, which is present on all of the large islands and, in some places has been recorded to reach a density of 500 per km (1,300 per sq mi). The Arctic fox ("Alopex lagopus") has been known to den on the islands, with several hundred observed in the 1980s. Other mammals occasionally observed include the wolf ("Canis lupus"), the polar bear ("Ursus maritimus"), ermine ("Mustela erminea"), Arctic hare ("Lepus timidus"), and reindeer ("Rangifer tarandus"). The discovery of Severnaya Zemlya is the subject of Veniamin Kaverin's novel "The Two Captains" as well as its stage adaptation, "Nord-Ost". Severnaya Zemlya