It is 1700 km long and divided into five parts, which can be followed in succession or indistinctly.
Alternating coastal and inland routes, this large Celtic loop combines the traditional Tro Breizh, which connects the cities of the seven founding saints of Brittany, with the more personalized Tro Breizh of St. Columbanus: two pilgrimages in one. Starting in Saint-Coulomb, this first part leads inland to Blain, towards the southern borders of Brittany. Starting in Blain, the second part leads to Locminé via a detour south of the Loire before returning to Brittany. Starting in Locminé, the third part goes up the southern coast of Brittany to Camaret-sur-Mer. Starting in Camaret-sur-Mer, the fourth part will take you to Guingamp on the north coast of Brittany. Departing from Guingamp, the fifth and final part takes you back to the start of the loop in Saint-Coulomb, visiting the interior of Brittany before returning to its northern coast.