After six weeks of exploring the wonders of our seas and oceans, the marine-life series concludes with a look at the worrying future our global waters face due to man-made threats.

Sir David Attenborough speaks to scientists who reveal the tragic plight of albatross chicks ingesting potentially fatal plastic, dolphins being poisoned by toxins and the terrifying bleaching of coral reefs due to rising water temperatures.

But hope is offered with inspiring conservation stories, including the team in the Caribbean who’ve turned around the fortunes of leatherback turtles by patrolling beaches to protect them from predators and poachers.

A moving and thought-provoking finale.