London's dark river and its secrets

Rust is seen along the bank of the River Thames during low tide in London, Britain February 24, 2017. The artery through which the world's trade passed at the height of the British Empire, its banks were lined with factories that drove the industrial revolution but left its waters biologically dead.

Bricks covered in mud are seen on the bank of the River Thames during low tide in London, Britain February 27, 2017. For Reuters photographer Stefan Wermuth most work days are spent a short stroll away from the Thames, covering the political machinations of parliament, the Bank of England or previewing a new exhibition at the Tate Modern gallery. A ramble along the river is a chance to take a breather from the frenetic pace of news to shoot in a slower and more creative way.

Sand is seen on the bank of the River Thames during low tide in London, Britain February 24, 2017. Over three months, Wermuth walked along the banks of the Thames, photographing the river and the abandoned objects exposed by the receding tide.

Seaweed is seen on the bank of the River Thames during low tide in London, Britain January 23, 2017.

Wooden props are seen on the bank of the River Thames during low tide in London, Britain March 9, 2017.

Water trails are seen on the bank of the River Thames during low tide in London, Britain February 24, 2017.

A wooden stick is seen on the bank of the River Thames during low tide in London, Britain January 23, 2017.

Stones are seen on the bank of the River Thames during low tide in London, Britain January 23, 2017.

Raindrops fall into the River Thames during low tide in London, Britain February 27, 2017.

Stalactites are seen along the bank of the River Thames during low tide in London, Britain February 24, 2017.

An umbrella is seen on the bank of the River Thames during low tide in London, Britain March 2, 2017.

Traffic cones are seen on the bank of the River Thames during low tide in London, Britain January 19, 2017.

A drawing of a face is seen on a wall along the bank of the River Thames during low tide in London, Britain February 24, 2017.

Water runs out of a bridge pillar along the bank of the River Thames during low tide in London, Britain January 23, 2017.