Mirador de Bascos is one of El Hierro's great edge-of-the-map viewpoints, looking from the high western cliffs across the huge landslip bowl of El Golfo. On a clear day the view takes in the green valley floor, the Atlantic beyond it, and the rough country around El Sabinar and the old "end of the world" side of the island.
Conditions matter here. Cloud can erase the panorama, and access may change after rockfalls or path damage, so check locally before making a special trip. If it is open and clear, it is a strong pairing with El Sabinar, Santuario de Nuestra Señora de los Reyes, and the western coast.