Career
Dallmann began his adventures at 15 as a young sailor. In 1866 he became captain of the Hawaiian ship West.C. Talbot, undertaking trading trips in the Bering and Chukchi seas to locations in Alaska and Chukotka. He was the first recorded European to set foot on Wrangel Island.
From 1867 to 1870 he commanded the whaleship Count Bismarck on a whaling cruise to the Pacific tropics, the Sea of Okhotsk, and the Bering and Chukchi seas.
In 1872/74, when the whales began to become rare in the Arctic waters, Dallmann was commissioned to explore the Antarctic seas on the sailing steamer Grönland. Still on the Grönland, he spent the 1875 whaling season as expert on the Davis Strait and Baffin Bay whaling grounds.
Between 1877 and 1884, on behalf of Russian financier Baron von Knoop, Dallmann made annual attempts to haul freight to the Gulf of Ob and the Yenisei Gulf to be exchanged for grain and other cargoes brought down those great Siberian rivers by means of barges. Owing to the ice conditions in the Kara Sea, of a total of seven attempts only four were successful.
Finally von Knoop stopped the difficult venture in order to cut losses.
Despite the failures, Dallmann had had the rare chance of exploring many Kara Sea islands and shores that few Europeans had seen. After leaving the Arctic waters forever, Dallmann became the Captain of steamer Samoa in 1884. His ship brought the "Otto Finsch Scientific Expedition to the (then little explored) northern coast of New Guinea.
Between 1887 and 1893 he kept exploring the northern coast of New Guinea on behalf of the German New Guinea Company.
Many islands and straits in that area were named by him during that time.