From the Panama Canal's opening day to present, nearly a million ships have passed through the mighty locks. Encompassing tragedy and triumph, Spanish kings, conquistadors and five different American presidents, the building of this massive project spanned 400 years. And today, nearly 100 years after its completion, the Panama Canal remains one of the most vital trade routes in the world. In addition to Panama's man-made marvel, this voyage includes some of nature's most amazing creations in the Caribbean, Mexico and Central America.