Where the Rhône swings around the northern edge of the Isle Crémieu, the river runs wide and green between limestone cliffs, with the Bugey hills rising on the far bank, and the villages of Bouvesse-Quirieu, Montalieu-Vercieu and Hières-sur-Amby sit along its southern side. It is a quiet corner, an hour from Lyon, that most people never think about, and on a hot day it is exactly where you want to be.
The swimming is real. At Montalieu-Vercieu there is a large leisure area on the Rhône with a supervised beach in summer, set on a broad stretch of slow water held back by the river works, and it is popular with families from Lyon on weekends. Away from managed areas, keep out of the main river: the current is strong and cold, and the hydroelectric works upstream can change levels without warning.
High above the river at Quirieu are the remains of a medieval fortified town that once guarded the crossing and the border between the Dauphiné and Savoy. Little is left except broken walls and a sense of space, but the view from the cliff edge over the Rhône is superb. Not far away, the plateau of Larina above Hières-sur-Amby is an archaeological site with traces of settlement from prehistory to the early Middle Ages, and at La Balme-les-Grottes a cave system has drawn visitors for centuries, including, legend says, the bandit Mandrin, who is supposed to have hidden there.
The Isle Crémieu itself is a limestone plateau of small lakes, marshes, woods and stone villages, crossed by narrow lanes that twist around rocky outcrops, ideal for riding at an easy pace. Crémieu, with its medieval market hall and old gates, is a lovely place for lunch. Across the Rhône, the roads into the Bugey climb steeply in hairpins to viewpoints above the river. The local stone has been quarried here for centuries, and you will see it in walls and farm buildings everywhere.
Montalieu has shops and basic services, and Tignieu, about fourteen kilometres away towards Lyon, is the nearest town of over five thousand people, with fuel and supermarkets. Arrive in late afternoon in summer, swim while the sun is still on the water, and the ride back to Lyon in the evening light will feel like a holiday.