Bakio is a municipality in the province of Biscay, in the Basque Country region of northern Spain. It lies on the Bay of Biscay coast, within the comarca of Mungialdea, roughly 30 kilometres northeast of the provincial capital, Bilbao.
The town is best known for its beach, Bakio Beach, a long sandy stretch at the mouth of the Estepona river that makes it one of the main surfing and summer resort destinations on the Biscayan coast. Offshore, the small rocky islet of San Juan de Gaztelugatxe — connected to the mainland by a winding stone bridge and staircase — is one of the area's most visited landmarks and lies within the municipality's boundaries.
Bakio is also known for the local Txakoli wine produced in the surrounding vineyards, a light, slightly sparkling white wine typical of the Basque coast. The municipality remains a largely residential and agricultural community whose population swells considerably during the summer months.