The GR34 is an amazing walking route around Brittany. Often this is the old Customs Trail around the coast (the customs officers who guard the coast to stop smugglers), starting at Vitre (Ille et Vilaine) and finishes at Saint Nazaire.

In 2017 the Finistérienne section was elected GR favourite of the French

Information on the whole route is difficult to find. There are no Apps I can locate and no single website covering the whole of the route. This may be because individual regions within Brittany maintain the route that goes through their region.

Below are some links which may be of assistance.

This site provides some maps and a GPX download https://www.traildino.com/trace/continents-Europe/countries-France/trails-GR34_-_Sentier_des_Doaniers

Camaret-sur-Mer to Audierne – https://ilovewalkinginfrance.com/coast-of-brittany/

GR34 Books – type in GR34 in the search – https://www.mongr.fr/
for example Morlaix to Brest – https://www.mongr.fr/trouver-prochaine-randonnee/parcours/gr-34-de-morlaix-a-brest-et-au-faou

Downloadable map – generalised but useful. Also have a look at Hike Bike Map – https://www.gpsies.com/map.do?fileId=qryivbjohdvbnaer

GR34 Topoguides – books for sale – https://bretagne.ffrandonnee.fr/html/283/topoguides-du-gr-34

Paper maps – https://ignrando.fr/boutique/cartes/randonnee-france.html?ign_pack=80747

https://www.brittanytourism.com/matching-what-i-want/hikes-in-brittany/gr-34-the-customs-officers-path/

https://www.outdooractive.com/en/route/long-distance-hiking/brittany/gr34-the-customs-trail-brittany-s-most-celebrated-hike/36678611/

GPX download – https://hiiker.app/trails/france/saint-malo/gr-34

This is the map of the GR34 section around Saint Cast

Cycling

There is also a famous Cycling Route which has received praise and it is called the EV4 -or EuroVelo 4. It goes from Roscoff to Dunkirk and then through many countries. There is no official guide for the whole cycle route.

https://en.eurovelo.com/ev4

When you start EuroVelo 4 in France, you cycle on La Vélomaritime, an iodized route that links the English Channel to the North Sea. With rocky points, bays, dunes, cliffs, UNESCO World Heritage sites and more, The Vélomaritime is a biking experience second to none over 1,500 km. EuroVelo 4 in France is linked to EuroVelo 5 – Via Romea (Francigena) and EuroVelo 1 – Atlantic Coast Route. From Calais to Bray-Dunes, the route is shared with EuroVelo 12 – North Sea Cycle Route.

Also https://en.francevelotourisme.com/cycle-route/la-velomaritime-eurovelo-4