Every June 8th, World Oceans Day invites us to reflect on the health of this vast blue frontier that regulates life on Earth. This year, the anniversary arrives with an air of cautious victory following the historic adoption by the UN of the High Seas Treaty, a legal framework designed to protect biodiversity in waters that do not belong to any country and which represent two-thirds of the marine surface. However, to understand the global health of the ocean, sometimes one must look at what is small.