Caissons floating after the dry dock has been flooded, 1965
![A dry dock with flooded structures and a mountain in the background](https://www.communitystories.ca/v2/pont-tunnel-louis-hippolyte-lafontaine_bridge/wp-content/uploads/sites/130/2020/01/PrtScr-capture_21.jpg)
Société d’histoire des Îles-Percées
The flooding of the dry dock took eight days. The perfectly sealed caissons floated to the surface despite their 32,000-ton weight. This is due to a phenomenon known as Archimedes’ principle, which states that if an object containing an amount of air equal to its own weight is immersed in a fluid at rest, it will be buoyed up by a force equal to the weight of the fluid displaced.