Hafan Prysor is in Trawsfynydd, right in Snowdonia. It's a stone cottage on a working farm. You get one good-sized bedroom for two people. It's a 5 Star place, which in my book means it's well-kept and has everything you need.
It's surprisingly spacious inside for a one-bedroom place. The lounge and kitchen are all one open area. Upstairs is just the bedroom and the bathroom. The ceiling's high up there with some old beams. The bed's a kingsize.
You can walk straight out from the door onto paths. The Coed-y-Brenin forest is about ten minutes down the road for mountain biking. Blaenau Ffestiniog is close by for things like Zip World and Bounce Below.
The coast is about a half hour drive. Harlech, Black Rock Sands, places like that. Dolgellau is a useful market town, about 15-20 minutes away for shops.
It's got a garden with a patio and a BBQ. There's bike storage, parking, a washing machine, and a dishwasher. All the bedding and towels are there. There's WiFi, but it's rural broadband, so it's fine for checking things but don't expect to stream films on multiple devices. Mobile signal depends on your network.
Useful links: Snowdonia National Park, National Trust Wales, and Coed-y-Brenin Forest.