The water bubbles before a man with a cyclops breaks the surface and announces that he has found a shopping cart on the bottom. A few minutes later, the cart has been pulled out of the water and placed in the pile of other debris that the divers have come across.
What they are mainly looking for are environmentally hazardous things such as boat batteries, tires and other things that can destroy the water in the lake.
Rotary initiators
One of the divers is Mattias Kressman from Stockholm.
"We want to clean the lake of things that destroy the drinking water," he says.
Behind the harbour day and the cleaning of the bottom is Rotary in Mariefred, where Kjell Kristiansen is president.
"It hasn't been done for many years, so we thought it was time now," he says.
In the clip, you see some of the finds that came to the surface.