In 2008, Spain began filling 300-metre-deep coal mine with 547 billion litres of water; four years later, the site looked nothing like it once did

For nearly six decades, coal mining transformed a part of Galicia in northwest Spain into an enormous open pit. The excavation at As Pontes eventually reached more than 300 metres deep, leaving behind a vast landscape scar after mining operations ended.

But instead of leaving the abandoned mine untouched, engineers embarked on an ambitious rehabilitation project. The enormous pit was deliberately filled with water, eventually creating what became one of Spain's largest artificial lakes.