He visited Bjørnøya in 1898 and 1899, exploring the viability of coal mining and eventually claiming ownership of the island as a territory of the German Empire.
This enterprise proved unsuccessful but raised some publicity, earning him the nickname "Nebelfürst" ("prince of the mists").
In 1908 after overwintering the polar night with Hjalmar Johansen in a cabin at Cape Boheman on Spitsbergen, he and Johansen travelled over the inland ice to Spitsbergen's northwest coast.