Scientific and research expedition “Lost Islands” to the Arctic Regions arranged by the “Finval” Research Centre has been successfully completed. 6 participants of the expedition sailed about 2700 km of difficult sea routes around the Taimyr Peninsula on a sail and motor trimaran “Finval”, and explored many Arctic islands. The expedition started at the Khatanga settlement and finished in the Dikson village on September, 4th. The expedition lasted for 45 days. Twice the trimaran was blocked by heavy ice: on the Preobrazheniya Island and on the South Peter Island; three times polar bears approached the trimaran and we had to frighten them urgently off; hurricane wind and storms many times tested the strength of the expedition participants and the vessel… During the expedition we collected unique scientific data on marine mammals (walrus, polar bear, true seals, cetaceans), terrestrial mammals, birds, molluscs, plants etc.