Greenpeace tours with the Beluga along the Danish, German and Polish Baltic Sea coasts to test water samples, here near Faaborg, Denmark. The water is tested for nitrate and phosphorous levels, temperature, oxygen and salt levels and for multi-resistant germs.
High numbers of animal factory farms lead to an increased production of liquid manure, which is later spread onto the fields, with traces eventually landing in the waterways after rainfall.
Samples taken form closer to the coast are brought back to the Beluga for testing.