Marseille abuts the spectacular Parc National des Calanques, a 20km stretch of high, rocky promontories rising from the turquoise Mediterranean. The cliffs are interrupted by small idyllic beaches, some impossible to reach without a kayak. The Marseillais come in droves to soak up sun or take long hikes. Protected since 1975, the promontories shelter a wealth of flora and fauna: 900 plant species, Bonelli’s eagle, and Europe’s largest lizard (the 60cm eyed lizard) and longest snake (the 2m Montpellier snake).
From October to June the best way to see the Calanques (including the 500 sq km of the rugged inland Massif des Calanques) is to hike the many maquis-lined trails. Marseille's tourist office leads guided walks (no kids under eight) and has information about trail closures. It also has an excellent hiking map of the various calanques .
In July and August trails close due to fire danger: take a boat tour from Marseille or Cassis , though they don't stop to let you swim. Otherwise, drive or take public transport, though roads are rough, parking scarce and the going slow. The roads into each calanque are often closed to drivers, unless they have a reservation at one of the calanque restaurants. You must instead park at a public lot, then walk the rest of the way in.
Sea kayaking from Marseille or Cassis is wondrous. Raskas Kayak organises sea-kayaking tours and tourist offices have details of many more guides.
For access to the calanques closest to Marseille, drive or take bus 19 down the coast to its terminus at La Madrague, then switch to bus 20 to Callelongue, a small calanque with restaurants. From there you can walk to Calanque de la Mounine and Calanque de Marseilleveyre along spectacular trails over the clifftops.