The most famous waterfall on this walk is Sgwd Y Eira, you can walk behind the waterfall, but when Derek went it was closed due to rock fall problems, so make sure you check before venturing into the falls. If it is shut then don't be disappointed - this walk will take you through five other equally beautiful waterfalls.

To guide him on this walk and give him an insight into the rock that makes up the waterfalls Derek has enlisted the help of Tony Ramsey, a retired professor of geology and Scientific Director of the Brecon Beacons Fforest Fawr Geopark, he knows this walk inside out.

On this walk you will be following the 'farewell rock', the band of sand stone that marks the end of the south Wales coalfield. When miners reached this rock they knew they had reached the end of the coal reserves, and it was time to say farewell and move elsewhere.

Near Pontneddfechan the sand stone towers above the path, and if you look hard enough it is a great place to see some fossils...

Tony says... the fossils that we see in this rock are plant fossils...they were laid down when we were in the tropics and the age of these rocks is approximately 316 million years. .

The first half of the walk follows the river Neddfechan and for just over a kilometre it is a nice easy path that you can push a pram or a wheelchair along, but be careful it can be uneven in parts. The path is a relic of the industrial heritage of this area; it is part of an old tramway used to transport silica rock from mines further up the valley..

Silica mining started here in 1822 and you pass some of the abandoned workings along the way....

Tony says... we call it silica rock, in this area it is known as the Dinas rock named in fact for this area. The rock was used to make fire bricks, the reason it was used for that purpose is because it is made from quartz, an extremely hard mineral, with a high melting point, and it can be used to make the bricks that line furnaces. They were exported to America, they were exported to Europe and to Russia, and in Russia silica bricks are still known as Dinas bricks..

The first waterfall you see on this walk is Sgwd Gwladys. .

It is formed by water flowing over hard sandstone into a plunge pool below made up of soft mud rock - and after all these years it's still a work in progress because the rock is continuously eroding (with this particular waterfall, 1.3 metres of rock is eroded approximately every 1000 years)..

The next waterfall is the Horseshoe Falls, in the Neath valley, surrounded by oak trees, it is simply beautiful.

Derek says... Two waterfalls down, and three to go, the first of the three is Sgwd Ddwli Isaf followed by Sgwd Ddwili Uchaf. And as the path climbs higher towards Pontmelinfach picnic area the waterfalls get more spectacular. .

After an hours ramble through lush tree-lined gorges the terrain starts to change, you emerge from the woodland canopy to find yourself on a hillside before dropping back down the Afon Mellte to the final waterfall on the walk, Sgwd Isaf Clun-Gwyn..

Before heading off to the end point of this walk, Cwn Porth car park, Tony arranged for Derek to take a different look at waterfall country. With the help of experienced caving instructor Gary Evans, and some professional safety gear they're heading underground....

Derek says... Obviously this isn't part of the walk and you should only come here as part of an organised tour led by someone like Gary who has all the right equipment and know how, and even though they take school children down here, be warned, people have lost their lives in this cave so don't be daft..

The river Mellte disappears underground at Porth Y Ogof, and although it doesn't look that dangerous it poses a threat to cavers, a threat echoed in its name....

Gary says... it's called the Mellte, which means lightning, because the waterfall levels come up so fast, it is something we have to keep an eye on. .

Like the rest of the walk, the cave systems have lots more geological interests to explore. Whether you're under or above ground this walk offers spectacular sights, plenty of water, plenty of rain but still plenty of places to see and enjoy, this walk is proof that you don't need the sun to shine to go walking in Wales.