Beginning at Kedarnath as the thaw sets in during May and 100,000s of pilgrims start their annual ascent, we go up through Yamunotri – not the source of the Ganges but of its sister the Yamuna – Badrinath, which has one of the holiest temples on the route, and up to Gangotri.

All along this route we get glimpses of the varied wildlife that make their home here, from rare photography of the snow leopard in the mountains, to the lammergeier which, with its 3-metre wingspan, is one of the largest birds of prey, and the langur or Hanuman monkeys in the huge deodar trees.

The film then shows the effects of the monsoon hail storms and rains, which give the river half of its flow-waters in just a few weeks, and helps wash down an astonishing 2 billion tons of sediment into the plains of India, making it the most fertile soil on Earth.

The monsoon when it comes brings back life to the river which has been drying up during the hot season and washes down an enormous amount of sediment from the mountains producing muds and soils that are estimated to be 3 miles deep in certain places.

Having watched the rise of the Ganges in the Himalayas and its flow through the plains of India, in the final episode we see the effect the river has when it meets the Bay of Bengal and forms the largest delta system in the world.

The delta itself is also home to the largest density of human population of earth, in a land around the size of Britain, six times more people find their living, and all thanks to the river, which not only brings water, but also fertile mud to the area making 3 rice crops a year possible.