Zheng He's fleets pioneered numerous new maritime routes, amassing extensive navigational expertise as they sailed from the Western Pacific across the Indian Ocean to the east coast of Africa. The breakthroughs made by Zheng He put China in the forefront of world navigation. Relying solely upon wooden ships and natural wind power, Zheng He overcame all manner of difficulties at sea. To accomplish this required not only advanced navigational and shipbuilding technology and extensive knowledge of marine conditions, but also the courage to venture into largely uncharted waters. Prior to this time, China's navigators were essentially limited to following coastal routes. Their voyages could not compare to those of Zheng He in any respect, including fleet and crew size, range, and duration.