Alexander von Humboldt at Mykonos, Greece on July 1, 2011. Photo © Peter Vnukoff

  Alexander von Humboldt at Istanbul, Turkey on June 28, 2011. Photo © Bart de Boer

  Alexander von Humboldt at Istanbul, Turkey on June 28, 2011. Photo © Bart de Boer

  Alexander von Humboldt at Mykonos, Greece on June 14, 2011. Photo © Michael Bragg

  Alexander von Humboldt in the Straits of Messina, Italy on October 28, 2010. Photo © Richard Maidment

  Alexander von Humboldt at Lisbon, Portugal on October 7, 2010. Photo © Rui Agostinho

  Alexander von Humboldt at Bergen, Norway on September 7, 2010. Photo © Kjell Christian Andersen

  Alexander von Humboldt at Isafjordur, Iceland on August 5, 2010. Photo © Brian Crocker

  Alexander von Humboldt at London, United Kingdom on June 7, 2010. Photo © Paul Bass

  Alexander von Humboldt at Funchal, Madeira, Portugal on November 6, 2008. Photo © Marcial Fernandes

  Alexander von Humboldt at Lisbon, Portugal on November 3, 2008. Photo © Peter Roberts

  Alexander von Humboldt at Funchal, Madeira, Portugal on October 18, 2008. Photo © Goretti Figueira

  Alexander von Humboldt at Funchal, Madeira, Portugal on October 18, 2008. Photo © Sergio Ferreira

  Alexander von Humboldt at Rotterdam, Netherlands on May 3, 2008. Photo © Bert Lamers

  Alexander von Humboldt at Rozenburg (Rotterdam), Netherlands on May 3, 2008. Photo © Cees de Bijl

  Alexander von Humboldt at Rozenburg (Rotterdam), Netherlands on May 3, 2008. Photo © Cees de Bijl

  Alexander von Humboldt at IJmuiden, Netherlands on May 2, 2008. Photo © Joop Sponselee

  Jules Verne at Alicante, Spain on October 31, 2007. Photo © Christopher D'haene

  Jules Verne at Barcelona, Spain on August 2, 2007. Photo © Jan Indekeu