The climb from the basilica to the lakes is a short road with a long reputation. Cyclists know it from the Vuelta, where it has been a summit finish with a brutal gradient, and the ramps are steep enough that you will use second gear more than you expect. Over about a dozen kilometres you rise from valley meadows to a high, rolling limestone shelf, and the road threads between steep grassy slopes with cow bells clanking somewhere in the mist. Expect hairpins, a narrow carriageway, and cattle that regard the tarmac as theirs.
At the top sit Lake Enol and Lake Ercina, two glacial basins in the Western Massif of the Picos de Europa, a little over a thousand metres up. They are not big lakes. What makes them is their frame: cropped turf, boulders, and peaks coming and going in the cloud. The area was among the first national parks established in Spain, in 1918, and the lakes are close to the heart of it. Cows wander and graze, which in these hills means cheese, and herders still work the high pastures in summer. A little past the lakes are the old mine workings of Buferrera, a reminder that this was also working country.
Mirador de la Reina, a viewpoint on the way up, gives a long look back toward the coast and is a good place to let the engine breathe. The weather can change quickly up here: fog, wind and a sharp drop in temperature are common even in July, and by the time you reach the top you may be riding in cloud with a few metres of visibility. When it clears, the rewards are enormous. Visit early in the morning if you can, since the road gets crowded later and in peak season private traffic can be restricted and replaced by a shuttle, so check ahead.
There is no pump anywhere near the lakes. Cangas de Onís, about fourteen kilometres away, is your nearest real town with a pump. A small seasonal café or two operates near the lakes, but do not rely on it, and carry water and a layer.