Semyon Ivanovich Chelyuskin (Russian: Семён Иванович Челюскин; c. 1700 – 1764) was a Russian polar explorer and naval officer. Chelyuskin graduated from the Navigation School in Moscow. He first became a deputy navigator while serving in the Baltic Fleet (1726) and later promoted to navigator (1733). Chelyuskin was chosen for the Second (Great Northern) Kamchatka Expedition, in which he took part until 1743. He participated in expeditions, led by Vasily Pronchischev and Khariton Laptev. In spring of 1741, Chelyuskin made a voyage from the Khatanga River to the Pyasina River by land. He described the western coastline from the Taimyr Peninsula to the Middendorff Bay and then from the mouth of Pyasina to the mouth of the Yenisei River. In winter of 1741–1742, he traveled from Turukhansk to t