Right up until the late 18th century, when the first weighted lines were used to probe the ocean depths, many people believed the seas were bottomless - the watery equivalent of infinite outer space.
When President Teddy Roosevelt posed for the cameras astride a massive steam shovel during construction of the Panama Canal in 1906, it was more than a simple photo op. Though the scene was clearly staged, it symbolized a crucial moment in American history.
Historically, maritime travelers had to pass around the entire mass of North and South America, including the bottom tip, the tempestuous Cape Horn, which was littered with shipwrecks.
Aside from its parks and nature areas, Singapore is intensively developed, and due to the shortage of land, is building up, down and on manmade islands and landfills.
Poor laborers from all parts of Asia as well as Africa, the Americas and even Europe are transported by plane each day to wealthier nations where low-tier jobs are plentiful; sometimes the travelers board without even knowing their final destination.
In our quest to define and describe the world, we have crisscrossed the oceans and continents, compiling exhaustive knowledge about its life forms and features, and extended our physical reach through technology, which provides us instantaneous and pervasive access to information about seemingly everything.
