1. A good web site is Derrik Brockway’s Weather Man Walking, that includes maps, route details and background information. I can make GPX files for any of these.

https://www.bbc.co.uk/programmes/articles/4r0gdLJc3Hnm7t0k2cD3ZP4/maps-and-route-information

Pont Nedd Fechan

2. Sgwd yr eira is on the river Hepste. The grand circular route crosses the river at the waterfall. Goes up via Porth Yr Ogof to the pub at Ystradfellte. (It is possible to omit the pub and cut across from Porth Yr Ogof and hence reduce the distance by well over a mile). It then crosses to the Nedd Fechan and follows the river back to the car park at Pont Nedd Fechan.  Sgwd Gwladus is just off the return route on the river Pyrddin, so can be visited via a short detour just before the end. The total distance is  ~10+ miles.

There are other options: 

3. A really appealing one is to walk to Penderyn after Sgwd Yr Eira and visit the distillery or Roy Noble’s son’s pub or both and retrace the route. ~ 8½ miles.

4. A second is a shorter circular of about 51/4 miles up via the Powder House and across to Nedd Fechan to visit Sgwd Gwladus on the way back.

Beacon’s Way

5. The Beacons Way from Storey Arms to Tafarn Y Gareg is ~ 15 miles so probably best broken down into 2 stages maybe near Ystradfellte. After Tafarn Y Gareg it continues to Llanddeusant via Fan Hir and Llyn Y Fan and then back to Garreg Llwyd and on to Carreg Cennen and beyond. We should definitely do some of this at some time.

St Illtyd’s Way

6. St Illtyd’s Walk from Pontardawe goes from near the old Police Station in Pontardawe, behind Rhyd – Y Fro and across the main road up to Mynydd Y Baran. To the Half Moon is ~ 8 miles. We should definitely do some of this at some time, and maybe more of his walk.

Henrhyd Falls

7. Henrhyd Falls has a linear walk along the river of ~ 3½ miles round trip. This can be extended into a circular walk of ~ 4 miles. It can be extended yet again to include a stop at the Pen Y Cae Arms for a pint, meal or better still both. Making the walk to about 4½ miles

Aberdulais Falls

8. Aberdulais falls is owned by the National Trust and has a museum and large water wheel as well as the falls, but there is an entry fee of £7 – 8. I have 2 cards, but one is a female but they may not notice. There is no real path/hike, but  a visit can be combined with a walk/cycle along the Neath Canal, which I know nothing about.

There are also the plane wrecks to think about as well as the walks I suggested previously.

Arwyn a cycle I intend doing some time is from Llandrindod – Llanwrtyd = 23½ miles  along National Cycle Route 8 & 43 (on roads). By train to Llandrindod and back from Llanwrtyd. GPX included.