"The UN's third World Ocean Assessment highlights severe pressure from pollution, industrial fishing, and climate change. Sea-level rise has doubled in rate compared to a decade ago, reaching 4.3mm per year in 2023. Only 27% of the ocean floor has been mapped by 2025, leaving deep-sea ecosystems poorly understood. The ocean has absorbed 90% of excess heat and 30% of CO2 emissions, leading to severe strain on marine biodiversity."