Ganga

High in the Garhwal Himalaya, meltwater pours from an ice cave at the snout of the Gangotri Glacier. Pilgrims call the spot Gaumukh, "the cow's mouth", and the icy stream that emerges is the Bhagirathi. A few days' journey downstream at Devprayag it meets the Alaknanda, and from there the united river is called the Ganga – India's national river and one of the most important rivers on Earth.

The Ganga leaves the mountains at Rishikesh and Haridwar and begins a long, slow journey across the plains of Uttar Pradesh, Bihar and West Bengal. Along the way it gathers the Yamuna at Prayagraj, the Ghaghara, Gandak and Kosi from the Himalaya, and the Son from the south. Near the Bangladesh border it divides: the Bhagirathi–Hooghly flows past Kolkata to the sea, while the main stream, called the Padma in Bangladesh, joins the Brahmaputra to form the world's largest delta, home to the Sundarbans mangrove forest.

A river of life and faith

The fertile alluvial soil of the Ganga basin has fed farming communities for thousands of years, and the basin is still one of the most densely populated regions in the world. For Hindus the river is the goddess Ganga, and bathing in it is considered purifying. Haridwar, Prayagraj and Varanasi – where the evening aarti on the ghats draws crowds every night – are among the holiest places in India, and Prayagraj hosts the Kumbh Mela, one of the largest gatherings of people anywhere.

Wildlife and conservation

The river is home to the endangered Ganges river dolphin, India's national aquatic animal, as well as the gharial and many species of fish and turtles. Rapid urbanisation has brought serious pollution, and the Government of India's Namami Gange programme, run through the National Mission for Clean Ganga, works on sewage treatment, riverfront management and biodiversity conservation.