A multi-million pound clean-up operation has cut sea pollution from a mine in north-east England.
Into a different world: At the lift shaft base
More than £3m was used to halt waste pumping into the North Sea from the Boulby potash mine in east Cleveland.
The improvements were part-paid for by cash from the European Union's Life Environment programme.
Now waste from the mine will be pumped back into cavities below ground.
The new facilities were opened by Yorkshire and Humber MEP David Bowe.
The mine is also the site of a unique ongoing scientific experiment.
Experts have created a laboratory at the mine to look for so-called "dark matter" in a cavern 1,100 metres underground.
It will lead the search for the vital component of the cosmos.
State-of-the-art detectors have been installed in a sub-surface observatory in the hope that its isolation and quietness will aid the search.
Dark matter is a fundamental though mysterious component of the Universe.
It could be in the form of sub-atomic particles that interact with normal matter only very weakly and are almost impossible to detect in a laboratory on the Earth's surface.
Boulby is one of the world's deepest working mines and, situated near the coast, its tunnels reach far out under the sea.
Boulby now hosts one of the world's most sensitive dark matter detectors called Zeplin.