A new coastal path has been completed this year and it means that you can walk the full 16km between Las Catedrales (Cathedral's beach) and Ribadeo. It is a mainly flat walk which meanders around the coast and uses a mixture of the tiny coast road (very quiet) and a newly created footpath. It is called the 'ruta de la costa' and is great because you can just do the bit of it that you want. You don't have to do the whole distance.
Click here for a map of the route. You can start at Las Catedrales, the beach famous for its rock arches, and walk east towards Ribadeo. There is quite a bit of the route on the road but other than the beaches, it is pretty quiet. Alterntively you can park in the picnic area at Rinlo (campo do cristo) and walk east. This part of the walk is mainly on the coastal path. The only bit on the road is as you leave Rinlo. You can either take a picnic or eat in one of the 4 great restaurants in Rinlo.
Probably the best place to park is between Rinlo and Ribadeo where there ae a couple of dilapidated buildings (an old toilet block and some sort of shelter). From here you can walk east (towards Ribadeo) or west (towards Rinlo. If you walk east, the path meanders around lots of secluded rocky bays with lots of flowers and wildlife. Look out for the Tongue Orchids in June. There are also a couple of ancient forts this way with description boards telling you all about them.
A final option is to park at Rinlo and walk towards las Catedrales (west). Not far from Rinlo you come to the cetaria de Rinlo. This is an old shellfish farm which is worth a look at. Look out for the nice brown donkey in the little village just after the shellfish farm.