The oceans are facing more threats now than at any time in history. Yet a nascent industry is ramping up to exert yet more pressure on marine life: deep sea mining. A handful of governments and companies have been granted licences to explore for deep sea mining in ecologically sensitive waters, and the industry is positioning its development as inevitable, but deep sea mining isn't happening anywhere in the global oceans – yet. Opening up a new industrial frontier in the largest ecosystem on Earth and undermining an important carbon sink carries significant environmental risks, especially in light of the biodiversity and climate crises facing the natural world and specifically our ocean. Rather, we need a strong Global Ocean Treaty that puts conservation, and not exploitation, at the heart of how governments approach the ocean.