More than half of the world's oceans are exposed to industrial fishing activities, a new study, conducted at unprecedented scale, reveals. Peak fishing activity, the study goes on to report, is more affected by cultural and political events such as holidays and closures than by changes in economic factors, or environmental ones. Given the vastness of the world's oceans, which cover roughly 70% of the Earth's surface, quantifying the extent of human fishing activity globally has been a challenge. However, David A. Kroodsma and colleagues saw a prime opportunity to better study fishing patterns as more and more vessels adopted automatic identification system (AIS) technology. AIS technology - which tracks a ship's identity, position, speed, and turning angle every few seconds - was originally meant to help ships avoid collisions. But here, Kroodsma et al. used the data from this system to study the global footprint of industrial fishing, processing 22 billion automatic identification system messages obtained from more than 70,000 industrial fishing vessels between 2012 and 2016. Their results show that industrial fishing occurs across more than 55% of ocean area, with a spatial extent more than four times that of agriculture. Global hot spots of fishing were seen in the northeast Atlantic and northwest Pacific, as well as in nutrient-rich regions off South America and West Africa. Remarkably, fleets from five countries (China, Spain, Taiwan, Japan, and South Korea) account for more than 85% of observed fishing efforts on the high seas, the authors report. Notably, they observed a large annual drop in mid-latitude fishing efforts that coincides with annual fishery moratoria in China, and a smaller drop at higher latitudes that corresponds with Christmas vacation in Europe and North America. Elvira Poloczanska discusses this study is a related Perspective.