Bwthyn Afon is in Tanygrisiau, just outside Blaenau Ffestiniog. It's a terrace cottage, solid stone, built for quarry workers. The back garden is enclosed so it's safe for a dog.
It sleeps five but that's a squeeze. Two bedrooms: one king size bed and the other has bunks plus a single. One bathroom. It's a 4 Star place, which means it's comfortable and well looked after. It's got central heating and a wood burner too, which you'll want in the winter.
The village is quiet. You're right by the Tanygrisiau reservoir. Good for a straightforward walk. Blaenau Ffestiniog is about five minutes drive for shops and chip shops.
You're in the middle of a lot. The Ffestiniog Railway station is in the town. You can get the train down to Porthmadog. Snowdon is about a 25 minute drive if you want to climb it or get the train up. The Zip World caverns are even closer, maybe 10 minutes.
For mountain bikers, Antur Stiniog is right there. For walkers, you're on the edge of the Snowdonia National Park. A lot of the good routes start within half an hour.
Inside, it's got what you need: washing machine, dishwasher, WiFi. Bedding and towels are included. You can bring one dog. There's bike storage round the back.
Useful link for planning: Visit Wales Adventure Activities.