‘Dark oxygen’ is being produced 13,000 feet below ocean surface, ground-breaking study finds

What is ‘dark oxygen’ and where is it coming from?The study published in the journal Nature Geoscience explains that the production of oxygen at such depths is thought to be impossible because there isn't enough sunlight for plants to do photosynthesis. But what makes this discovery so strange is that, in this case, oxygen is not being produced by plants.