Llyn Trawsfynydd

• A walking and cycle track runs around the water, and the marked cycle loop is roughly eight miles, which you can start from Trawsfynydd village or the Lake Centre.
• Cyclists should expect one steep section of about 400 m near the main dam; the rest is easier going.
• On foot, route guides put the full circuit at about 8.6 to 8.8 miles and anywhere from 3.5 to 5 hours, with difficulty rated easy to moderate depending on who you ask. Treat it as a half-day outing rather than a stroll.
• The circuit mixes lake views, woodland and mixed paths with some roadside walking, including stretches near the A470, and crosses a narrow footbridge at the southern end.
• Dogs are welcome on a lead.

• The lake holds natural wild brown trout, regularly stocked rainbow trout, plus perch, rudd and pike, and is one of the better fishing waters in the national park. Fishing is managed by the Prysor Angling Association, with a fleet of boats available.
• You need the appropriate permit and a national rod licence.
• Canoes and kayaks must be registered, paddlers must wear a lifejacket, and inflatables are not allowed.

Expect varied waterfowl across the open water and margins, with otters also present. Ospreys are often seen fishing here between April and September, which is the best window if you are hoping for one, though sightings are never guaranteed. Bring binoculars and be patient near quieter margins.

• The Lake Centre (Canolfan Prysor) is the main visitor hub, with a café overlooking the water, fishing tackle shop and permit office, toilets and showers, bike hire, fishing boats, a car park and a hatchery.
• There is also a lake car park near the southern end of the circuit, close to the footbridge. Parking arrangements can vary, so have a plan B.
• Bring waterproofs, boots with grip, and water and snacks if you are doing the full loop.

• Parts of the circuit are beside traffic, including the A470, so it is not a fully traffic-free loop.
• Muddy sections are common in wet weather.
• The decommissioning site on the shore is a visible industrial presence in many views, and some visitors find it jars with the mountain setting.
• The loop is longer and hillier in places than it looks on a map, so judge the distance before setting off with young children.