There is aboundant Vasconic toponimy in Iberia, of course.
Country of the ancient Cantabri:Edit
Very common are names in -oño, -oña (obviously Basque oin: foot, meaning a hill or mountain as in Begoña, Toloño, Ogoño, Garoña...), in -aya, -ayo (aia: rocky peak, Sp. peña). Also singular names like Santander (sant-andere: sant + "lady": holy lady), Barreda, Zurita , Aés (aitz?), Iruz, Bárcena, Selaya (zelaia), Ubiarco, Garabandal, Andinas, Arriondas, etc. Add the names in -eda(s) (from -eta, example Muriedas, similar to Murrieta) and in -ega (from -aga, example Noriega).
All this is consistent with the Cantabri being mentioned in Roman sources as not just allies but also relatives of the Aquitani, whose Basque identity is beyond doubt.
It should be mentioned that the Cantabrian Wars were partly fought in the Western Basque Country, in areas of the Autrigones and Caristii tribes. This lack of a clear distinction between Cantabri and Western Basque tribes extends to the Early Middle Ages, when the Goths destroyed the City of Cantabria (believed to have been somewhere near Logroño) and created the Duchy of Cantabria (again believed to be roughly in modern La Rioja). The Sierra de Cantabria separates La Rioja from the Araban plain.
Some Spanish Celto-centric linguists speculate on Celtic identity of the area at the time of Roman conquest based on toponyms such as the Deva river (also in Gipuzkoa, written as Deba). While it's true that it is difficult to argue for a Basque root of this name, the Celtic speculation is also without substance because deva as goddess is Indo-Iranian, not Celtic. Celtic for god are different words like dia or duw, related to dev and deva, yes but clearly not the same word at all. A Latin origin (deus, dea) makes better sense but still not quite it.
Overall the ancient Cantabrian and Astur area totally lacks the usual Celtic toponyms like seg-, -briga, -dun.
Cantabrus as such could well be originally Ganetaburu, i.e. the chief or summit (buru) of the peaks (ganeta ← gain/gane + -eta). Similarly the North Galician Artarbri (sing. Artabrus) should be the chief of the holly oak (Q. ilex): arte + buru = artaburu.