The Cantabrian Mountains stretch east–west, nearly parallel to the Cantabrian Sea, as far as the Pass of Leitariegos, also extending south between
León and Galicia. The range's western boundary is marked by the valley of the river
Minho (), by the lower
Sil, which flows into the Miño, and by the
Cabrera River, a small tributary of the Sil. The Cantabrian Mountains reach their south-western limit in Portugal. As a whole the Cantabrian Mountains are remarkable for their intricate ramifications, but almost everywhere, and especially in the east, it is possible to distinguish two principal ranges, from which the lesser ridges and mountain masses radiate. One range, or series of ranges, closely follows the outline of the coast; the other, which is loftier, forms the northern limit of the great tableland of
Castile and León, and is sometimes regarded as a continuation of the Pyrenees. In some parts the coastal range rises sheer above the sea, and everywhere has so abrupt a declivity that the streams which flow seaward are all short and swift. The descent from the southern range to the high plateaus of Castile is more gradual, and several large rivers, notably the
Ebro, rise here and flow to the south or west. The breadth of the Cantabrian chain, with all its ramifications, increases from about in the east to about in the west. Many peaks are over high, but the greatest
altitudes are attained in the central ridges on the borders of
León, Asturias,
Palencia and
Cantabria. Here are the highest peak
Torre de Cerredo (),
Peña Vieja (),
Peña Prieta () and
Espigüete (); an unnamed summit in the
Picos de Europa, to which range the Peña Vieja also belongs, rises on the right bank of the
Sella to a height of ; further west the peaks of
Manpodres,
Peña Ubiña,
Peña Rubia and
Cuiña all exceed . A conspicuous feature of the chain, as of the adjacent tableland, is the number of its parameras, isolated
plateaus shut in by lofty mountains or even by precipitous walls of rock. The Cantabrian Mountains sharply divide "
Green Spain", to the north, from the dry
central plateau. The north facing slopes receive heavy
cyclonic rainfall from the Cantabrian Sea, whereas the southern slopes are in
rain shadow. ==Main ranges==