 When authorities drained this 200-year-old canal, what they found at the bottom was extraordinary. It's a great January day in Paris, and a crowd has gathered along the canal Saint Martin. As they stare into the murky brown depths below, the waters slowly empty, uncovering secrets that have been kept hidden for many years. And as the bottom of the 200-year-old canal emerges into view, a truly bizarre underside of the city is revealed. The story of the famous canal began in 1802, when the French leader Napoleon, I ordered its construction. At the time, around 550,000 people were living in Paris, and the population was continuing to grow. Napoleon therefore hoped that canals bringing fresh water to the city would help to prevent the spread of disease. As a result, over the next two decades, three canals were dug across the city, together totaling more than 80 miles in length. Arguably the most famous of the three, the Canal Saint Martin, connects the 68-mile canal de l'Orc with the long, lazy flow of the river Seine. Beginning in Basin de l'Arcenal by the Seine, the canal travels underground beneath Place de la Bastille, the site of a prison that was stormed during the French Revolution. It subsequently emerges close to the Place de la République before heading north to the Basin de la Vallette. There, it joins with the canal de l'Arc and the river Orc-Beyond. In total, the canal Saint Martin covers some three miles of central Paris. Originally funded by a levee on wine, it historically brought trade as well as fresh water to the city. In fact, in its heyday the waterway also carried both building supplies and food to the people of Paris. Today the canal is more popular as a leisure destination for locals and visitors alike. Paris wealthy young Bohemians can often be seen congregating on its banks and in pavement cafes. Meanwhile, the picturesque bridges are a magnet for tourists exploring the city. Over time, in fact, the canal has become an iconic symbol of the city. As well as having inspired painters such as the British impressionist Alfred Sisley, the waterway has, throughout the years, featured in a number of movies including the 2001 classic Amelie. Inevitably though, almost 200 years of operation have taken their toll on the canal. As a result, officials now make an effort to empty it every 10 to 15 years, removing the detritus that has found its way to the bottom. However, in January 2016 they were in for a shock. The last time that the canal had been drained was back in 2001, when authorities retrieved some 40 tons of trash from the water. In addition, they uncovered a car, washing machines, gold coins and two 75mm shells, the latter dating from World War I. Since then, the area around the canal St. Martin has become famous for its nightlife, with young people flocking to the previously exclusive district. That said, there were concerns that these revelers would bring even more waste to the waterway, and in 2016 it was time to find out if they had. On January 4 work began on the mammoth task of emptying the canal. Indeed, the project would take 3 months and involve shifting some 3 million cubic feet of water. It would also cost the city over 10 million dollars, but it needed to be done. First, workers drained the water from the canal until just 20 inches remained. Next, it was time to evacuate the fish. For 3 days, the team rushed to catch the bream, trout and carp that live in the muddy waters, subsequently removing them to safety in another section of the waterway. Then, on January 7 the rest of the water was emptied from the canal. The waterway's secrets were finally revealed for the first time in 15 years, and what was exposed at the bottom amazed witnesses, who had gathered on the canal's footbridges to have a closer look. Indeed, while much of the rubbish revealed at the bottom of the canal was of the sort that you might expect, items such as glass bottles, shopping bags and traffic cones, some of it left locals puzzling over exactly how such objects had ever ended up in the water. In fact, among the most common objects revealed as the water levels dropped were bicycles, particularly ones from the city's Velob hire system. Launched in 2007, this scheme brought some 14,500 bikes to the streets of Paris. Sadly, however, many of them seem to have met an unfortunate fate. It's like some kind of weird submarine treasure, one witness, Mark, told The Guardian. I just can't believe the quantity of Velob's in there. I guess they were stolen and thrown in afterwards. It's bizarre. Moreover, bicycles weren't the only strange things to have found their way to the bottom of the canal. Even more unbelievably, a pair of motorbikes were also revealed as the waters continued to drop. Yet how did such expensive pieces of equipment end up dumped in the canal? The truth may never be known, and there were yet more mysteries waiting to be discovered. Alongside the bicycles and motorbikes were supermarket trolleys, chairs, dustbins and suitcases, all scattered across the muddy surface. There were stranger oddities, too, a ghetto blaster-style music player, for example, and even an abandoned toilet bowl. Together, they painted a fascinating picture of life along and under the canal. That's Paris for you, onlooker Bernard commented. It's filthy. What's more, apparently it's only getting worse. The last time, I don't remember seeing so much rubbish in it, he continued. I despair. The youngsters are using it as a dustbin. Yet despite this, is there hope for the future of the Canal Saint-Martin? Well, with the litter problem laid bare for everyone to see, authorities have seized the opportunity to speak out against the problem. If everyone mucks in and avoids throwing anything into the water, Deputy Mayor Celia Blauel told the MailOnline, we might be able to swim in the canal in a few years. Rather her than us.