The Sentier Martel that schleps along the bottom of the Gorges du Verdon is one of the supreme hikes in Europe, by a country mile. It takes about 6 hours and boasts everything: ascent/descent, mountain streams, vertical ladders and pitch-black tunnels. We saw eagles too.
My top tip: park at Point Sublime, call a taxi from La Palud and get dropped off at the easterly start (ChÃ¢let de la Maline). Hike back. Enjoy a well-deserved beer at the bar. Drive home knackered, but enriched.