El Hierro is first and foremost an island for people who like wild landscapes and clear water. The diving around the island — among the best in Europe — draws serious enthusiasts from across Spain and beyond. The rock pools and natural swimming coves are excellent. Inland, the hiking through ancient juniper forests and volcanic terrain rewards those willing to do a bit of walking.
The island's renewable energy story is worth seeking out: the Gorona del Viento wind-and-pumped-hydro facility has allowed El Hierro to run entirely on renewable power for extended periods, and it's a genuinely interesting piece of infrastructure to visit. La Frontera's dramatic El Golfo valley, formed by a prehistoric landslide, is the most spectacular landscape on the island. Pico de Malpaso, the island's highest point at 1,501 metres, offers views on clear days to La Palma and the other western Canary Islands.