The coverage area of human activity is so wide, our ocean infrastructure footprint is equivalent to the footprint of cities on land—and it’s poised to grow in the coming decade, creating a bizarro real-life Waterworld. Human seaward expansion provides some benefits to natural ecosystems, but the message in the findings published on Monday in Nature Sustainability is clear: The world has to be deliberate or risk further screwing over the seas.

These findings are the first of their kind to map humanity’s watery footprint. The researchers mapped a range of human activities happening both nearshore and far offshore, including oil rigs, pipelines, cables, fish farms, ports, and offshore wind farms. The findings show that 12,355 square miles (32,000 square kilometers) of seafloor, an area about the size of Maryland, have been directly colonized by human activities and infrastructure. But that physical footprint only tells part of the story; all told, up to 1.3 million square miles (3.4 million square kilometers) of seascapes have been impacted by human activities. That includes noise from ports and other knock-on effects.