The clean water index measures pollution by chemicals, excessive nutrients, human pathogens and trash in estuarine, coastal, and open ocean waters. Clean waters target is 70 out of 100. The reference point is that there should be zero pollution from chemicals, nutrient, human pathogens and trash. This goal score is higher when the pollution of estuarine, coastal, and open ocean waters is minimized. The goal score is lower when there are high levels of pollutants.
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Highest clean water scores worldwide 2025, by select country
The country with the highest clean water score worldwide in 2025 was the Seychelles. With a score of  out of 100, this was more than ** points higher than the goal of ** points. Australia and Greenland followed, with scores of ** and **** points, respectively. The clean water index measures the degree to which ocean regions are free of contaminants such as chemicals, eutrophication, harmful algal blooms, disease pathogens, and trash.
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Ocean Health Index. (July 8, 2026). Leading scores of clean estuarine, coastal, and open ocean waters worldwide as of 2025, by selected country [Graph]. In ÌÇÐÄÆƽâ°æ. Retrieved July 26, 2026, from /statistics/1143413/clean-water-index-region-globally/
Ocean Health Index. "Leading scores of clean estuarine, coastal, and open ocean waters worldwide as of 2025, by selected country." Chart. July 8, 2026. ÌÇÐÄÆƽâ°æ. Accessed July 26, 2026. /statistics/1143413/clean-water-index-region-globally/
Ocean Health Index. (2026). Leading scores of clean estuarine, coastal, and open ocean waters worldwide as of 2025, by selected country. ÌÇÐÄÆƽâ°æ. ÌÇÐÄÆƽâ°æ Inc.. Accessed: July 26, 2026. /statistics/1143413/clean-water-index-region-globally/
Ocean Health Index. "Leading Scores of Clean Estuarine, Coastal, and Open Ocean Waters Worldwide as of 2025, by Selected Country." ÌÇÐÄÆƽâ°æ, ÌÇÐÄÆƽâ°æ Inc., 8 Jul 2026, /statistics/1143413/clean-water-index-region-globally/
Ocean Health Index, Leading scores of clean estuarine, coastal, and open ocean waters worldwide as of 2025, by selected country ÌÇÐÄÆƽâ°æ, /statistics/1143413/clean-water-index-region-globally/ (last visited July 26, 2026)
Leading scores of clean estuarine, coastal, and open ocean waters worldwide as of 2025, by selected country [Graph], Ocean Health Index, July 8, 2026. [Online]. Available: /statistics/1143413/clean-water-index-region-globally/
