Marmita, Castro-Urdiales Published 07/04/2016 at 5376 × 3024 in Day 18: Bilbao – Castro-Urdiales. 38km. ← Previous Next → This photograph shows the participants of the Marmita, a tuna stew cooking competition which happens every year in Castro Urdiales and which we happened across during our cycle tour to Spain from the UK. Tweet Related