The GR 34, the whole coast of Brittany on the customs officers' path.

The GR 34 is the slowest and most complete way to see Brittany: a trail that follows the coast almost without leaving the sea, from cove to headland and from harbour to harbour. It is called the customs officers' path because it began as the patrol route of the agents who watched for smuggling, and even today it passes their stone lookout huts. Nobody does it all in one trip: you choose a stretch and walk a few days.

What is the customs officers' path?

After the Revolution, in 1791, a customs corps was created to patrol the Breton coast, and its men opened a continuous path hugging the cliff to see every cove. During the 20th century it was abandoned, and from the late 1960s walkers gradually recovered it: the first long-distance stretch opened near Lannion in 1968, and in 2008 the Breton coast was waymarked continuously. A 1976 law also guarantees a three-metre right of way beside the sea for pedestrians.

Today the GR 34 is about 2,000 km long. It starts at Mont-Saint-Michel, in Normandy, and ends at Saint-Nazaire, on the Loire estuary, after crossing six départements. In 2017 the Finistère stretch was voted the French people's favourite GR. The waymarks are those of all French GRs: a white stripe over a red one.

How do you get there and walk it?

By car from Spain, Saint-Malo is about 720 km from the Irún border, and the Pink Granite Coast about 830. By plane, the useful airports are Nantes, Rennes and Brest. The high-speed train from Paris reaches Saint-Malo, Brest, Quimper, Lorient and Vannes, and from those stations regional buses leave for the coastal villages.

The trail is walked in stages of 15 to 25 km, from village to village, sleeping in campsites, guesthouses or hotels. The comfortable way to do a stretch is to settle in one place and move by bus or local taxi to get back to the car. Many stretches can be done as a circuit, returning through the interior.

The terrain is more demanding than it looks: there are no great heights, but the path climbs and drops continuously between the coves and the cliff, and in Finistère the cumulative ascent in a day can be considerable. The tides matter: at some points the path crosses beaches or estuaries that can only be passed at low tide, and there are waymarked variants for high tide.

Which stretches are worth it?

In the north, Saint-Malo is the walled corsair city where the sea rises about 13 metres on spring tides; at low tide you walk out to the islands, and the GR continues towards Dinard and Cap Fréhel. Further west, the Pink Granite Coast is the most famous stretch of the whole trail: between Perros-Guirec and Trégastel the pink rocks take impossible shapes, and the Ploumanac'h walk is 5 km that takes about two and a half hours.

Finistère concentrates the cliffs. The Crozon peninsula has the Pen-Hir headland, Camaret and Morgat, and the GR goes right round it in two or three days. To the south, the Pointe du Raz is the tip of Cap Sizun, facing the island of Sein, with the Pointe du Van next to it.

On the south coast, the trail changes character: less cliff and more gulf. At Carnac and the Gulf of Morbihan you walk among thousands of aligned menhirs and along the shore of an inland sea full of islands.

When to go?

May, June and September are the best months: long days, heather in bloom on the cliffs, free places in campsites and car parks and the sea still mild in September. July and August are good for walking, but the coastal villages fill up, everything has to be booked and the car parks at the headlands are saturated by midday. From November to March there are spectacular storms and empty paths, but many places to stay and almost all campsites close, and rain and wind are the norm.

How many days do you need?

A weekend is enough for a short stretch, such as the pink granite or the Crozon peninsula. With a week you walk a whole sector of 100 to 150 km, for example from Saint-Malo towards Cap Fréhel or the full circuit of Crozon. Walking the 2,000 km takes months: those who do it all usually spread it over several holidays across the years.

What is worth knowing before going?

Wild camping on the trail is not generally permitted: a good part of the coast is protected land and many municipalities ban it, so the sensible thing is to plan with campsites. Always bring a waterproof, even if the day starts clear, and check the tide timetable before stretches that cross beaches. Erosion forces the route to be diverted from time to time; respect the diversions and do not go near the cliff edge. There are fountains and bars in the villages, but on headland-to-headland stretches there can be several hours without services.