The Urdaibai estuary, formerly known as the Mundaka or Gernika estuary, is a natural reserve at the mouth of the river Oka, which originates in the neighbourhood of Zugastieta in the municipality of Muxika in Bizkaia, where several springs converge. It was named after the now ruined tower of Urdaibai (urde ‘pig’ and ibai ‘river’) back in the 1970s. (more…)