Despite freezing, navigation is a major human activity on the Laptev Sea with the major port in Tiksi. During Soviet times, the Laptev Sea coastal areas experienced a limited boom owing to the first icebreaker convoys plying the Northern Sea Route and the creation of the Chief Directorate of the Northern Sea Route. The route was difficult even for icebreakers – so "Lenin" (pictured) and her convoy of five ships were trapped in ice in the Laptev Sea around September 1937. They spent an enforced winter there and were rescued by another icebreaker "Krasin" in August 1938. The major transported goods were timber, fur and construction materials. Tiksi had an active airport, and Nordvik harbor further west was "a growing town," though it was closed in the mid-1940s.