To study the effects of ocean acidification, ten huge plastic containers called mesocosms are in place in the Gullmar Fjord in Sweden. The project is unique: mesocosms of this size have never been used for such a long period of time. The experiment is part of a worldwide research project, and includes researchers from the University of Gothenburg, Sweden. The mesocosms were lowered into the fjord with the help of divers from the research vessel Alkor and each one will now enclose 55,000 litres of seawater, containing organisms from the winter waters of the Gullmar Fjord.