An RSPB reserve, Ynys Hir is made up of salt marshes, wet grassland and woodland - part of which is said to date back to the 17th century.

There are seven hides dotted around the thousand acre sanctuary, offering spectacular vantage points across the estuary. There are also several marked nature trails - the shortest route is 0.5m and the longest three miles.

Ynys Hir is probably best known for its Greenland white-fronted geese. Every year, about 150 of them fly in to spend the winter in this part of the world. It's their only regular wintering site in the whole of Wales and England.

Winter is also a good time to see other wildfowl. At this time of the year, the estuary attracts thousands of ducks such as wigeon and teal as well as Canada geese.

In the spring and summer, the oakwoods attract two species of woodpecker in addition to the usual woodland species. The RSPB has put up special bird boxes around the reserve which are used every year by more than a hundred pied flycatchers.

The Dyfi estuary is also one of the few strongholds for breeding lapwing and redshank in Wales. Feeding cormorants, goldeneyes and red-breasted mergansers can be seen from the Domen Las Hide.

Even if you're not a keen bird-watcher, Ynys Hir is a lovely place to go for a walk - especially in the spring when the woodlands are carpeted with bluebells.

The RSPB puts on special events at the reserve. For details, visit their website (see below).

Opening Times Reserve open daily 9am to 9pm (or sunset when earlier). Visitor Centre open March to October, daily 10am to 5pm, and from November to February, from 10am - 4.00pm Wednesday - Sunday. Admission Charges Non-members - £2 per car which includes access to the nature reserve. Telephone 01654 700222 Tourist info: 01654 702401 Directions The visitor centre is signposted from Eglwys-fach, 1 mile/1.6 km off A487. By bus, from Machynlleth or Aberystwyth get off at Eglwys Fach. Website www.westwales.co.uk/rspb.htm The BBC is not responsible for the content of external websites.