The Arctic is rapidly transforming into a navigable ocean because of global warming. Consequently, a large percentage of the sailing distance between Europe and Asia could be saved by alternatively sailing through the Arctic. However, taking Arctic routes is fraught with risks and additional costs due to sea ice. The major purpose of this study is to improve safety and fuel efficiency of Arctic ships, which is achieved by voyage optimization upon frequently updated meteorological, oceanographic and ice forecasting. The resistance model accounts for both ice thickness and ice concentration of unconsolidated Arctic sea ice in summer. Ice-induced risks defined in the Polar Operational Limit Assessment Risk Indexing System (POLARIS) are dealt as constraint. Other constraints such as avoidance of land and shallow water are also included. These functions are demonstrated by the two case study vessels sailing between Rotterdam and Shanghai via both the Arctic and the traditional routes.