Azores on the island of Pico, is the highest point in Portugal, at . If measured from their base at the bottom of the ocean to their peaks, which thrust high above the surface of the Atlantic, the Azores are actually some of the tallest mountains on the planet. The climate of the Azores is very mild for such a northerly location, being influenced by its distance from the continents and by the passing Gulf Stream. Due to the marine influence, temperatures remain mild year-round. Daytime temperatures normally fluctuate between and depending on season. Temperatures above or below are unknown in
Azores caldeira", the noted hot springs grotto. In 1869, the author Mark Twain published "The Innocents Abroad", a travel book, where he described his time in the Azores. The first reference to the island of São Jorge was made in 1439 but the actual date of discovery is unknown. In 1443 the island was already inhabited but active settlement only began with the arrival of the noble Flemish native "Wilhelm Van der Haegen". Arriving at Topo, where he lived and died, he became known as "Guilherme da Silveira" to the islanders. João Vaz Corte-Real received the captaincy of the island in