Arctic marine ecosystems have experienced profound and rapid changes over the past several decades. These changes have spurred a variety of efforts to evaluate ecologically important marine areas in the Arctic and to examine the need for conservation to enhance the resilience of these globally unique ecosystems. As part of its two-year term as chair of the Arctic Council, the United States has prioritized a process to evaluate the creation of an ecologically significant network of Marine Protected Areas in the Arctic. This primer is designed to inform and facilitate that process by summarizing and mapping previous major efforts to describe ecologically important marine areas across the Arctic. We recognize that site specific descriptions and evaluations are underway in individual countries and at different scales, and this primer is in no way meant to supplant those more exhaustive efforts….