Llyn Brianne: South Wales’ biggest body of water is a true recluse

When we moved to remotest Carmarthenshire, the place we heard recommended to us again and again for a day trip was Llyn Brianne.

Some places fall far short of the hype. Some, you finally get there and think ‘OK, nice enough.’ Some just totally exceed expectations. Llyn Brianne belongs firmly to the latter group.

Llyn Brianne from the dam ©Kerry Walker

This snaking reservoir nestles hidden in the upper Tywi Valley, spread-eagled on the borders between north-east Carmarthenshire, southeast Ceredigion and western Powys, and heading here to hike, bike, kayak or simply drive along the legendary single-track mountain lanes surrounding this lonely body of water, you’ll have one of the few opportunities in Wales to pass through three different counties on a day out.

Canadian-style remoteness!

Lonely is, indeed, the operative word when it comes to describing Llyn Brianne. The way most people arrive is from the market town of Llandovery on a winding 11-mile road up the Tywi River, through increasingly hilly pastureland with the first bare southern peaks of the Cambrian Mountains pressing in after you pass the scattered hamlet of Rhandirmwym to heighten the drama of the approach (NB: construction work on another dam on the Tywi was marginally marring parts of the rollercoaster road up to the dam in 2020 but this seems mostly over). Civilisation has been honed down by this point to a couple of farms and a nature reserve and then, after you pass the farm at Ystradffin and turn up the approach road to the dam, it virtually disappears altogether. All inky greens and cobalt blues in summer and at times almost monochrome in winter, hemmed in by dense spruce forest on three sides and craggy moors on the other, the first impression of Llyn Brianne coming this way is of a vista reminiscent of the Canadian forests in Alberta or Saskatchewan.

Of dams and mines…

Such is the impression the reservoir creates on the landscape that it’s hard to imagine that it did not exist until the early 1970’s, when the Tywi and other waterways were dammed to create Wales’ second-biggest reservoir by water volume, and South Wales’ biggest by far. Fittingly, it supplies a sizeable chunk of the region with water including Swansea, Neath and the South Wales Valleys. Before that, the area was known for its mining. The legacy of this is still vividly imprinted on the land around Llyn Brianne in the form of stark quarries, old mining apparatuses and even place names (Rhandirmwym means ‘land of minerals’ in Welsh). But mining’s effect on the surroundings is nothing compared to seeing the dam suspending this reservoir far above the riven valley up which you have climbed.

What to do

The spillway at Llyn Brianne – down the UK’s highest dam. ©Kerry Walker

See the sights! The dam is the main one here, and as this is what holds the whole thing in place and it’s the tallest dam in the UK, it’s worth gawping at this and the water surging under the bridge you’ll be watching from and down the wide spillway to the River Tywi twisting through the tumbling valley below. There are two viewpoints for the dam: the first left hand turn once the Llyn Brianne road reaches the top of the hill gives great views of the spillway from afar;  the second offers close-ups of the rushing water. In the hot weather of 2018, the water level dropped so much that you could even see the farmhouse that originally stood in this valley before it got flooded for the reservoir. Then there are the mine workings visible around the main car park. Otherwise it’s just about enjoying the spectacular scenery: pine forest, grassy river valleys and open boulder-strewn moor.

Hike! So many options here. The main walk people do is across the dam and along the good track which curves around the open southern shore of the reservoir to the edge of the forest. Tracks then follow round the reservoir via a forestry commission house visible on the far shore and right around Llyn Brianne (about 25 miles for a complete circuit) with the first half along the west/northwest tendrils of the reservoir to Soar y Mynydd Chapel on tracks and the second half along the northern and eastern sides on lanes (note paths do not follow the lakeshore exactly for most of the way). Most, however, make it an out-and-back walk from the car park/toilets and turn around soon after the forest starts. A path at the forest edge also bears sharp southwest to descend to Allt Rhyd y Groes Nature Reserve. A mile back down the road towards Rhandirmwym, there is also the Gwenffrwd-Dinas RSPB Reserve and the hike to Twm Siôn Cati’s cave. We’ll be featuring more of the best of the Llyn Brianne area’s Cambrian Mountains hikes in detail on the site soon!

Bike! A great day/ half-day’s cycle would be to do the hiking route around Llyn Brianne described above. The lanes around the northern/eastern sides of the reservoir are twisty and narrow but quite traffic-free.

Drive! The eastern and northern sides of the reservoir can be driven around on breath-taking single-track lanes. It’s slow-going but great fun, with routes continuing to Soar y Mynydd Chapel (northwest of the reservoir), Abergwesyn (northeast of the reservoir) and eventually right on to Tregaron, for routes further on into Ceredigion. Soar y Mynydd, Abergeswyn and Tregaron are all worthy stops in their own right, of course – we already write about them a lot on here and because we have a special love for this area you can expect us to write on them much more in the near future. In fact, our new series of Wales Road Trips (all found in the Explore area) launched in January 2021 and our scintillating Road Trip from Llandovery to Tregaron via Llyn Brianne (with a stop at Soar y Mynydd) is such a favourite of ours we made it the very first featured on the site!

Wildlife Watch! Red kites for sure, and this is one of the last domains of the red squirrel in England and Wales.

Star Gaze! The car park at Llyn Brianne is now a Dark Sky Discovery Site! And it is part of the Cambrian Mountains Astro Trail, linking prime star-gazing sites across Mid Wales.

NEXT ON THE JOURNEY: It’s 15 miles southwest from Llyn Brianne to one of our favourite Mid Wales forests, Caio Forest.

At a glance

How to get there: 11 miles north of Llandovery. Follow Cilycwm Road under railway bridge to Rhandirmwym (7 miles) then stay on east side of river to continue via Ystradffin Campsite and Gwenffrwd-Dinas Nature Reserve to Llyn Brianne. Our Road Trip: Llandovery to Tregaron via Llyn Brianne details more.

Parking: Two car parks at southern corner of reservoir. One with public toilets. Two further car parks on eastern edge of reservoir.

Refreshments: Bring your own picnic (stock up at Llandovery Co-op) or backtrack to pubs at Rhandirmwym (Royal Oak, 4 miles southwest) or alongside the Upper Tywi River (Towy Bridge Inn, 3.5 miles southwest). Check the pub opening hours, which are sporadic – there is no disappointment like rocking up at a country pub having worked up a thirst on the trail only to find it closed!

Best time to visit: Late summer or early autumn for glorious light and colours on the water and surrounding woods.