The Gorges de la Restonica is the great walk from Corte. A road follows the river for about 15km from the town to the Bergeries de Grotelle car park, from which a well-marked trail climbs steeply through boulders and pine forest to Lac de Melo, about an hour up. The fitter and more sure-footed can continue another 45 minutes to Lac de Capitello, perched in a rocky cirque just below the island's central ridge.
The gorge itself — all pink granite walls, rushing water, and deep swimming holes — is beautiful throughout. The lower section makes for good scrambling and bathing even if you do not intend to reach the lakes. In July and August the car park fills early; either get there by 8am or take the shuttle bus from Corte. The trail to Melo is busy; the continuation to Capitello is quieter and worth the extra effort.