The Rusanov expedition, led by geologist Vladimir Rusanov, was a 1912 Russian expedition to the Arctic, with an initial objective of establishing mineral claims on Spitsbergen. Following completion of its official programme, Rusanov expanded the expedition's scope to include an investigation of the Northeast Passage, though it remains unclear exactly which route he proposed to take. Rusanov's ship Hercules reached Novaya Zemlya in August 1912, where he sent a message that he was continuing east; this was the last ever heard of the expedition and its 11 personnel.
Artefacts found decades later on islands off the Taymyr Peninsula show that Rusanov managed to round Novaya Zemlya and cross the Kara Sea, and suggest that at least some of the party survived well into 1913, and possibly later. It is generally thought the expedition met an unknown fate in the area of the Pyasina estuary: it has also been suggested that Rusanov, an experienced Arctic explorer, went as far east as Severnaya Zemlya and the Laptev Sea. The fate of Hercules and its crew remains one of the great mysteries of Russian exploration of the Arctic.