Today marks the 100th anniversary of the official opening of the Panama Canal. A formidable project that was initially undertaken by France in the 1880s, abandoned, and later resumed by the U.S. in 1904, construction of the canal cost $375 million, and it’s estimated that tens of thousands of workers lost their lives, primarily to diseases like malaria and yellow fever. (Read more about the construction of the Panama Canal.) Once completed, though, the canal revolutionized maritime trade by slashing voyage time between the Atlantic and Pacific Oceans from several weeks to a mere 15 hours; it has been recognized as one of the seven wonders of the modern world. In honor of the canal’s centennial, here are five things you may not know about this engineering feat:

1. What was the first ship to travel through the canal? An American steamer known as the S.S. Ancon made the inaugural transit, carrying a cargo of cement, on August 15, 1914. Originally named the S.S. Shawmut, the ship was re-named after Panama’s Ancon Hill and the township of the same name. However, the Ancon’s sister ship, the S.S. Cristobal, made the first unofficial transit 12 days prior (also carrying cement).

2. What was the smallest toll ever paid to cross the canal? Tolls are calculated according to a vessel’s size and cargo, among other factors. According to the Guinness Book of World Records, Richard Halliburton paid the lowest toll in the canal’s history: just 36 cents. That’s because in 1928, the 28-year-old American traveler, adventurer, and author became the first person to swim the canal’s 77-kilometer length, making the trip over the course of eight days. By comparison, the cruise ship Norwegian Pearl paid US$375,600 in tolls in 2010. The average toll today is around US$54,000.

3. What do camels have to do with the canal? Since work began on canal expansion in 2007, scientists have been studying the dredged earth, uncovering more than 6,000 fossil samples—including fossilized remains of horses, monkeys, rhinos, and miniature, hump-less camels, plus an extinct predator known as the “beardog”—and identifying 10 new species based on fossil finds. Their research has also provided new data on the formation of the Central American land bridge. The isthmus was believed to have arisen about 3.5 million years ago, but researchers’ discoveries now suggest it may have been millions of years earlier.

4. Who was “the man”? “A man, a plan, a canal: Panama!” The origin of the palindrome is unclear, but it’s widely believed that the “man” in question was President Theodore Roosevelt. In the early 1900s, Panama was still part of Colombia, which had declined to grant land rights to the U.S. for construction. Under some controversy, Roosevelt provided support to Panamanian rebels for a revolution, who in turn granted the land to the U.S. (When Roosevelt later visited Panama in 1906, he became the first U.S. president to travel overseas.) Interestingly, in his 1903 State of the Union address, Roosevelt said that the people of Panama rebelled against Colombia "literally as one man."

5. What’s next? The current expansion of the canal will create a new lane of traffic and two new locks, plus widen and deepen the existing channels. The expansion is projected to cost US$5.25 billion and to be completed in 2015. Meanwhile, another transoceanic canal is in the works, this one in Nicaragua: the country has granted rights to the China-based HKND Group for an alternate canal that would be wider and deeper than Panama's newly expanded one. Construction on the 278-kilometer project, which would pass through Lake Nicaragua, may begin as soon as December 2014.