San José del Pacífico sits on Highway 175 between Oaxaca City and the Pacific coast. The road is slow and winding; from Oaxaca City, count on about three hours by van or car in normal conditions.
Shared vans run from Oaxaca City toward the mountain towns and coast, but schedules and comfort vary. If you are prone to motion sickness, plan for the curves rather than pretending they will be fine.