The Cantabrian legislation divides the autonomous community in administrative regions called comarcas, but traditionally, other subdivisions of the territory have been used.

Administrative regions

Law 8/1999 of Comarcas of the Autonomous Community of Cantabria of 28 April 1999 establishes that the comarca is a necessary entity, integral in the territorial organization of the region. This law opens the development of the commercialisation in Cantabria promoting the creation of comarcal entities, which have barely begun to appear. The law establishes that the creation of comarcas will not become mandatory for the whole territory until at least the 70% of it had not been commercialised by its own will. It also adds that Santander will not ruled by commercialisation and should establish its own metropolitan area instead.

Comarcas in Cantabria have not reached administrative nature and barely have definite borders. Only Liébana for its geographic position in Picos de Europa, Trasmiera and Campoo, in the Ebro basin are established are clearly defined comarcas in the region. Nevertheless, functional differences in the territory can be distinguished, dividing it in the following areas: Santander Bay, of industrial and urban nature; Besaya, also industrial; Saja-Nansa, eminently rural; Western Coast, which has urban character; Eastern Coast, vacational; the traditionally renowned Trasmiera; rural Pas-Miera; Asón-Agüera, also mainly rural; the very well defined Liébana, and Campoo-Los Valles, rural and industrial by regions.

Natural regions (regarding geographical features)

Coastal strip

Central strip (Cantabrian valleys perpendicular to the coast): Liébana, Saja and Nansa, Besaya, Pas and Miera (or Valles Pasiegos), and Asón-Gándara valleys.

Southern strip (Rivers Ebro and Duero’s basins): Campoo and Southern valleys

Historic regions

Until the 13th century, Cantabria was organized in valleys, as was typical in all of northern Spain. From then on, it was substituted by the organization in cities, towns or historic comarcas that grouped several valleys.