The largest permanent saltwater lagoon in Europe is very sick, says 71-year-old campaigner Isabel Rubio, and what is so sad is that the devastation has been caused by human greed.

For the people living and working near the Mar Menor, “it is as if we have suddenly found ourselves living next to a garbage dump,” she says, fighting back tears. The devastation of the lagoon is one of the greatest ecological collapses in Europe, in what was once one of the most beautiful areas of Spain.

Rubio has lost hope that the protected body of water that juts out into the Mediterranean in the south-east of Spain will be restored in her lifetime, but says she will fight “to her last breath” in the hope that one day it may be healed.

As a child, Rubio would spend her summers swimming in the crystal-clear waters of lagoon, once home to vulnerable species such as seahorses and European eels, but now when the weather gets warmer, the 135km2 body of water becomes a green soup...