1. River Trent, Anchor Church, Ingleby, Derbyshire
The great river Trent, artery of the coalfields and industrial heartlands of the east Midlands, doesn't sound promising, but there are plenty of bucolic stretches to explore. I like the extraordinary caves of Anchor Church, a mile upstream from Ingleby near Derby, where the river has carved out a series of rock grottos. Hermits and saints have inhabited this remote place since the sixth century, adding windows and fireplaces. The swimming, in a quiet lagoon just off the river, is safe and it's a perfect place to explore with children or to shelter from the rain.
2. River Thames, Pangbourne, Berkshire
This is one of the best wild swims within easy reach of London. Get off the train at Pangbourne and head upstream three miles via the ancient oaks of Coombe Park. You're right on the edge of the Chilterns here and you'll find a wonderful wild stretch of river with chalky banks, clear water – and not a building in sight. Continue for another three miles to the pretty pubs in Goring-on-Thames, then jump on the train home. Alternatively walk or swim downstream from Pangbourne – it's six miles back to Reading – taking in the meadows with views of the historic Mapledurham house.
3. River Dart, Staverton, Devon
At Totnes jump on a restored steam train that runs on the South Devon Railway for the three-mile trip up the line to Staverton village. You'll find a gentle and relatively warm stretch of the river Dart – deep and still above the weir and more secluded, with little beaches, downstream. Follow the path downstream from the station for 20 minutes, beyond the weir, and you'll come to a superb jump on a corner bend, with steps built up the trunk of an old oak tree that overhangs the pool. It's an exhilarating plunge into the dark, peaty water below.
4. Kailpot Crag, Ullswater, Lake District
Ullswater is one of the most popular and beautiful lakes in the Lake District, but to escape the crowds head for this high, gnarly crag. There are twisted oaks and rowan trees, and a brilliant jump from the crag into deep, clear water. With its west-facing aspect it's a perfect place for swimming at sunset, and there's a beach alongside where you can brew up and make supper.
5. River Stour, Fordwich, Kent
Fordwich is thought by some to be England's smallest town. Set off from the old town hall and follow the path downstream along the Stour. The river is at first open and sunny, but becomes wooded and secretive after two miles, before winding through the reedy lowlands of the Stodmarsh nature reserve, good for spotting bittern, marsh harriers and water vole. You can only reach this section by swimming or canoeing.