show Abstracthide AbstractIn summer 2017, the Canada C3 expedition travelled on the MV Polar Prince icebreaker along the Atlantic, Arctic and Pacific coastlines of Canada, from Toronto to Victoria via the Northwest passage, collecting surface water samples throughout the journey. eDNA metabarcoding targeting multiple marker genes provides an extensive inventory of metazoan species, ranging from zooplankton to marine mammals across three connected oceans. This dataset was used to map the distribution of coastal marine metazoans, determine major biogeographic breaks along the coastline of Canada, and assess spatial patterns of biodiversity.