The Mistério da Prainha is a lava field extending from the humid highland of the Achada plateau all the way down to the N coast of Pico. It goes back to an eruption in 1562-1564. As the area is not usable for cattle grazing, it is mostly covered by natural vegetation such as heathlands, here around 800 m asl. The volcanic cone Cabeço do Mistério (816 m) shown in the centre of this picture was one of the sources of the lava.