From the Sanctuary of Volastra, trail no. 6d leaves: it is a trail cut into the mountainside, running parallel to the SP road leading to Vernazza and Monterosso. After about 2 km you will reach a locality known as Case Pianca (460m asl). From here, follow trail no. 7a, easily developing downhill across the woodland, among old dry-stone walls, and reaching the areas above Corniglia (90m asl). Here abandon trail no. 7a and follow trail no. 2 connecting Corniglia with Vernazza.
Once you reach the town of Prevo, turn right, taking trail no. 7b. Shortly after, you will meet the carriage road. Follow it for about 300m until you reach a steep mule track leading to San Bernardino and to Madonna delle Grazie Sanctuary.