Llyn y Fan Fach
This is a super waterside walk through a particularly beautiful section of the Brecon Beacons. The walk starts at a parking area north of the lake and takes you along the Afon Sawddle to the lovely Llyn y Fan Fach. It's a good track that climbs steadily towards the lake where you will first reach the Dam before climbing to Bannau Sir Gaer on the western side of the water. From here there a truly wonderful views over the lake and surrounding mountains.
The lake is a great place for bird spotting. Look out for red kite, common buzzard, kestrel, carrion crow, common raven and skylark as you make your way around the water.
The Brecon Beacons Way runs past the lake so you could pick this up and head east to Llyn y Fan Fawr to continue your walk. Heading north would take you to Llanddeusant with wonderful views over the Black Mountains.