Could the artificial introduction of oxygen revitalise dying coastal waters? While oxygenation approaches have already been proven successful in lakes, their potential side effects must be carefully analysed before they can be used in the sea. This is the conclusion of researchers from GEOMAR Helmholtz Centre for Ocean Research Kiel and Radboud University in the Netherlands. In an article in the scientific journal EOS, they warn: Technical measures can mitigate damage temporarily and locally, but they are associated with considerable uncertainties and risks. Above all, they do not offer a permanent solution because the oxygen content will return to its previous level once the measures end, unless the underlying causes of the problem, nutrient inputs and global warming, are not tackled.