Largely out of sight, criminals pillage the oceans. They steal millions of tons of fish each year. That is a huge economic loss to coastal nations, estimated to be somewhere in the tens of billions of dollars. It is an even larger threat to food security; a billion people depend on fish as their source of protein, and in many of the countries that are most dependent, one fish in three is stolen. Illegal, unreported and unregulated (IUU) fishing undermines governments’ efforts to manage their resources and undercuts the millions of fishers who are playing by the rules.