Bilbao city itself does not have a beach, as it lies inland a little, however they are a number of gorgeous beaches just along the coast from the estuary of the River Nervión. Many are also easily reachable by public transport from the centre of Bilbao. Ereaga and Sopelana are accessible via line 1 on the metro. No excuses then to take your kids to have a great time building sandcastles.