So what's beneath the surface of a Paris canal?

The Canal Saint-Martin, which was made famous in the film Amelie, is set to reveal all its secrets.

A huge engineering operation begins on Monday to clean the canal, which runs through east and central Paris down to the River Seine from the Bassin de la Villette.

The draining of the canal has got everyone asking a few questions:

The canal, seen here flowing towards the Seine River, will be drained by Monday evening. Photo: The Local

How will it be done?

It sounds complicated but actually looks quite simple and there’ll be no pumping needed.

On Monday engineers erected a small and unspectacular dam at the top of the canal by Place de la Bataille de Stalingrad. This will stop the flow of water and allow for the two-kilometre canal and the locks to be emptied one by one. In all 90,000 cubic metres of water will be emptied out.

Here's a closer look at the first lock getting drained. 

Each lock gate or sluice will be opened gradually from the top of the canal downwards to allow the water to gradually flow out into the Seine, without causing the river to flood.

The water should have drained away by Monday evening.

After that the heavy machinery will move in to remove silt and whatever else has found its way into the murky waters since 2001 – the last time the canal was cleaned.

A man in a wetsuit braves the chilly water to put the finishing touches on the dam. Photo: The Local

So what will be found?

If you were a betting person, you’d stake all you own on there being at least one Velib bicycle in the canal, in fact the amount of city bikes pulled from the canal could possibly reach double figures.

There’s a fair bet there’ll be one or two scooters in there and perhaps even a car, who knows.

Due to the fact that the banks of the canal are thronged by revellers in the summer there’s a good chance the canal is full of thousands of empty beer and wine bottles and probably a few picnic hampers.

And how many have dropped their mobile phones in the canal over the years trying to take photos?

Julien Gaidot, the engineer in charge of the operation said that previous experience of cleaning Paris canals means he expects to find discarded guns and other weapons.

And he may have already been proved correct. The Local spotted a gun lying on the bottom of the first lock on Monday just underneath the footbridge to Quai de la Loire although engineers told us they had no idea whether it was real or not. We'll have to wait and see.

Two World War shells were even found the last time it was cleaned and some pieces of gold.

There may be even more macabre finds given the fact that numerous people have died in the canal over the years.

However anyone who has lost anything in the waters has been warned to stay away and not attempt to retrieve it.

“We are concerned that people may venture in and try to find their belongings,” said Gaidot.

The draining process began on Monday morning. Photo: The Local

What about the fish?

No need to worry, the fish of the Canal Saint-Martin will be looked after. “We will leave 50 centimetres of water as the canal is drained to allow the fish to reach the Seine,” said Gaidot.

And those that do not reach the river will be fished out by a company which specialises in these kind of operations and moved out to safe waters.

A closer look at the new dam. Photo: The Local

What about the disruption?

Apart from the inconvenience to the fish, the main disruption will be for the tour companies which run guided canal boat trips.

A man working for one of the companies operating along the banks said he didn't think an empty canal would have an enormous impact on business. 

"Winter is typically quiet for us anyway, tourists generally prefer to get out on the water in the summer," he told The Local. 

"But it's a shame, we based this business here mainly because of the Canal Saint-Martin."

He added that the company would instead send its barges to the north east along the Canal de L’Ourq as well as along the River Seine.

With the canal all fenced off along the quays the trendy Parisians of the tenth arrondissement will have to find somewhere else to smoke, play the guitar and drink wine out of the bottle. Although being winter, only hardened hipsters will be displaced.

As for residents living along the canal, engineers promise there will be little disruption to traffic and there won’t be any work carried out at night.