The Arctic Ocean is one of the planet's most pristine marine regions, protected by its ice pack from the effects of commercial fishing, oil and gas development and shipping. But climate change is rapidly melting the permanent ice of the Arctic Ocean, causing a restructuring of its marine ecosystem and increasing human access. Commercial fishing currently does not occur in the international waters of the central Arctic Ocean—an area as big as the Mediterranean Sea known as the Arctic “donut hole.” But this could quickly change. As sea ice continues to melt, fish are likely to respond by swimming north. Industrial fishing vessels may follow, unimpeded by existing international law. The introduction of large-scale commercial fishing into these relatively unexploited waters could have extremely negative consequences, especially at a time when this sensitive ecosystem is stressed by climate change.