Local authorities evacuated the areas as a precaution
Five bombs have exploded in northern Spain, including four at popular seaside resorts.
The first bomb detonated outside a bank in the town of Getxo, north of Bilbao.
Two devices exploded at midday in the resort of Laredo, in the Cantabria region, before another two went off in Noja, some 20km (12 miles) from Laredo.
Officials said the Basque separatist group Eta had warned of the attacks, and nearby areas had been evacuated. One woman was treated for shock.
Emergency authorities received the call telling them Eta had planted four bombs on the beaches in Laredo and Noja, and Noja's golf course, which would explode between 1100 (1000 GMT) and 1400.
However, there were no other casualties as the beaches in the resort towns were virtually deserted because of rainy weather.
Eta regularly targets tourist resorts for its summer attacks.
Eta has killed more than 820 people in its 40-year campaign for independent Basque homeland in northern Spain and south-western France.
The group announced a ceasefire in March 2006 but formally ended it last June.