The walk starts from Bowden Bridge car park (SK22 2LH), a small Peak District National Park Authority car park in an old quarry on Kinder Road, about a mile east of Hayfield. It has 27 spaces and can get busy at peak times. Charges apply from 9AM to 6PM every day: £2.10 for up to 1 hour, £3.40 for up to 2 hours, £5.50 for up to 4 hours or £6.60 for the day, so for this walk get the all-day ticket. The machine takes coins only and gives no change, or you can pay with the RingGo app (location 51705), up to 24 hours after you park because the signal is poor. There's no overnight parking. Public toilets are just across the stone bridge by the car park entrance. Check the latest prices here.

Below the western edge, about half a kilometre from the edge path you walk before the Downfall, lies a shallow moorland pool. It was already marked on a map as Mermaid's Pool by 1840, and people around Hayfield told of a woman who lived in its water. Most called her a mermaid, others a nymph. The best known version says that she shows herself at Easter, and that anyone lucky enough to see her will live forever.

The story can be traced through old books and papers. In 1869 Henry Kirke published a poem, The Mermaid's Pool, in The Reliquary, about a young man who falls in love with the mermaid and drowns in the pool. A year later the Glossop-Dale Chronicle reported that people went up to the pool at Easter to look for her, and in 1872 the Glossop Times told of a Hayfield man who was made immortal by a strange woman who lived in the hillside.

In 1893 Robert Charles Hope wrote in his book on the holy wells of England that a nymph was said to bathe in the pool every day, and that any man who saw her would become immortal. Later writers added a real local man, Aaron Ashton, who died in the 1830s and was said to have climbed to the pool every Easter and lived to 104. Some people think the mermaid was made up quite recently, but the folklorist Simon Young argues that stories of a woman in the pool were really being told locally in the early 1800s.

Kinder Reservoir, which you walk beside at the start of this hike, was built because Stockport needed more water. Stockport Corporation took over the local water company in 1899 and began looking for new supplies straight away. The engineer James Mansergh chose this valley above Hayfield, and Abram Kellett of Ealing was hired to build a stone dam and a standard-gauge railway to carry materials and workers to the site. Two Acts of Parliament were needed to approve the railway, and two farms were lost to make way for the reservoir.

The line ran on from Hayfield's railway, skirting the cricket field and running up the Sett valley, and a well-known photograph shows a contractor's engine crossing Church Street in the middle of the old village. Some of the navvies and their families lived in a small settlement of temporary huts a little way down the valley. Work began in 1903, but the ground proved difficult, and in 1905 building stopped and the design was changed from a stone dam to an earth one.

Stockport Corporation and Kellett then ended up in the courts over money, and the Corporation ended his contract. Work started again in 1908 under G H Hill and Sons, and the reservoir was officially opened on 11 July 1912. As well as supplying Stockport, it controls the River Kinder, which had caused serious floods in Hayfield. The cobbled path beside the dam follows an old incline once used to haul materials up the hillside, and the course of the old railway can still be traced in places.