Lanestosa is a town and municipality in the province of Biscay, within the autonomous community of the Basque Country in northern Spain. It is a small municipality situated in the far west of the Basque Country.
The town lies in the westernmost part of Biscay, near the boundary between the Basque Country and the neighbouring region of Cantabria. Its position on this western edge gives it a peripheral character within the province and the wider autonomous community.
Lanestosa is notable chiefly for its small size and its location at the extreme western limit of the Basque Country, distinguishing it from the larger and more prominent municipalities of the region.