Brittany.

Brittany has roughly 2,800km of coastline — more than any other French region — and most of it is walkable on a single trail. The GR34, the "sentier des douaniers" (customs officers' path), was cut in 1791 to give Napoleonic customs officials a way to watch for smugglers, and it runs from Mont Saint-Michel down the entire Atlantic façade to the Pointe du Grouin and beyond. Modern walking holidays here are almost all stages of the GR34, broken into manageable hotel-to-hotel weeks.

The most distinctive section is the Côte de Granit Rose, the Pink Granite Coast in the northwest — a 30km stretch around Perros-Guirec where the rock weathers to colours between salmon and rust, sculpted into balanced boulders that look like a sculpture park designed by the tide. The Emerald Coast, the Côte d'Émeraude, runs east from there: dune-and-cliff country, gateway towns at Dinard and Saint-Malo, and the corner where the path reaches Mont Saint-Michel.

The walking itself is moderate by the GR34's reputation — gentle to undulating, with stretches of beach as well as cliff and footpath. Daily distances on packaged weeks tend to be 14-20km, hotel-to-hotel with baggage transfer. Tides matter: a few sections of the coast are walkable only at low water, and operators build their day plans around them.

Brittany has roughly 2,000 hours of sunshine a year, more than the British south coast, but it gets weather. April-June and September-October are the best windows — calm enough for the cliff sections, warm enough for the beaches, quiet enough on the path. July and August fill up with French families on holiday and the harbour towns get busy.

Headwater, Macs Adventure and Inntravel all run packaged Brittany walking weeks; the trip Mooch lists from Le Boat covers Brittany's inland canals rather than the coast, for anyone who wants the same region by water.