A number of technological advances made it possible for Europeans to range further into the seas during the Age of Exploration. One was the adaptation of instruments such as the astrolabe and the compass for more effective use on ocean voyages. Another was the development of sturdy but highly maneuverable craft such as the caravel, which was used on Portuguese and Spanish voyages of exploration, including those of Christopher Columbus. Other advances included the knowledge gained from previous voyages themselves. Improved maps, charts, and knowledge of currents, lands, resources, and native peoples enabled further exploration. For this reason, explorers often took great pains to document their excursions, keeping track of depth soundings, river crossings, and natural features to pave the way for future exploration.