The Picos de Europa are themselves quite remote, with two main access points from outside the region - Oviedo (air, bus, train) and Santander (air, ferry, bus, train). Depending on your mode of transport, options are as follows.
Air. The two closest airports to the Picos de Europa are Asturias (near Oviedo) and Santander (in Cantabria). Asturias airport. Easyjet fly to Asturias from London Stansted and Geneva; Iberia fly from Madrid and Barcelona; and other air companies serve other airports (see for more details). Santander airport. Ryanair fly to Santander from London Stansted and seven other European cities, as well as Madrid and Alicante; other air companies serve other airports (again see for more details). Cars can be hired at either airport. See the car section below for how to drive to the mountains, and the bus and train sections for public transport connections.
Car. Driving from the west. Driving east from Asturias airport, Portugal or Galicia, the best approach is the E70 coastal motorway, taking the Arriondas exit onto the N634, and from Arriondas turning south on the N625 for Cangas de Onís (1½ hours from Asturias airport). Driving from the east. Driving west from Santander airport or ferry terminal, the UK or France, along the E70 coastal motorway, you will approach the Picos de Europa from the north - via Arriondas and Cangas de Onís for the western massif (take the Arriondas exit for the N634; 2 hours from Santander airport), or Arenas de Cabrales for the central massif (take the Unquera exit for the N621 to Panes, then the AS114 to Arenas de Cabrales; 1½ hours from Santander airport), or Panes and Potes for the eastern massif (stay on the N621 to continue south from Panes to Potes; 1½ hours from Santander airport). Driving from the south. Driving north from Madrid and the rest of Spain, there are three options: via León and Oviedo to Arriondas and Cangas de Onís (6hrs from Madrid); via Valladolid and Palencia to Posada de Valdeón on the south side of the Picos de Europa (5½hrs from Madrid); and via Burgos to Potes (also 5½hrs from Madrid). See for more details. During the high season from July to September, some access roads into the mountains are closed to private vehicles during peak times - from  Covadonga up to the lakes of Ercina and Enol (Cangas de Onís is the best bet for parking, and where the buses start their route); and from Arenas de Cabrales to Poncebos - buses and taxis run frequently along these routes instead.
Ferry. The closest ferry-terminal is Santander in Cantabria, 1½ hours drive from Potes (via Unquera), or 2 hours from Cangas de Onís (via Arriondas). Ferries run to and from Plymouth and Portsmouth, and carry cars and bicycles as well as foot passengers - for times and information, see Cars can be hired at the train station, a ten minute walk from the ferry terminal. See the car section above for how to drive to the mountains, and the bus and train sections below for public transport connections.
Bus. Long-distance buses connect Arriondas (7km north of Cangas de Onís) and Unquera (40km north of Potes) to far-flung destinations such as Paris, Bilbao, Santander, Oviedo, Gijón, La Coruña, and Santiago de Compostela (see There are 2 or 3 buses per day from Santander to Potes, some continuing to Fuente De (see for the timetable). The most useful public transport in and around the mountains is on Alsa buses, and their services are rather limited ( Several buses a day run from both Arriondas and Cangas de Onís to Covadonga. In summer, when the road from Covadonga up to lakes Enol and Ercina is closed to cars, buses run from Cangas de Onís and Covadonga to the lakes. Alsa also connect Oviedo with Arriondas, Cangas de Onís, Arenas de Cabrales, Panes, and Unquera; there is one bus per day in each direction. There are also occasional buses from Llanes on the coast to Arenas de Cabrales. In summer, when car access to Poncebos and the Cares Gorge is restricted, buses run from Poncebos to Arenas de Cabrales regularly. Cheap taxis also ply this route. In summer there are buses from Cangas de Onís round to Oseja de Sajambre and Posada de Valdeón.
Train. Long-distance trains connect Oviedo and Santander to the rest of Spain, and beyond, but get no closer to the Picos de Europa (see The Feve narrow-gauge railway shuttles slowly along the north coast, between País Basco and Galicia, stopping in Santander on the way, but the closest stops to the Picos de Europa are Arriondas (7km north of Cangas de Onís) and Unquera (40km north of Potes) - see Feve trains carry bicycles for free and without needing to book in advance.
Cable-car. The only cable-car into the Picos de Europa is at Funte De.
Funicular railway. Alsa also run the funicular railway from Poncebos to the mountain village of Bulnes, the only other option being on foot.