This lift lock was the world's first in many ways

The Peterborough Lift Lock was built in 1904, and it was a considerable accomplishment in many ways, especially for the time that it was constructed. It is the first lift lock built with concrete and it was also the largest structure in the world that was built from unreinforced concrete. For many years, the Peterborough Lift Lock was the tallest hydraulic boat lift in the world.

What is even more remarkable is the fact that this lift lock operates without requiring any power. It operates on gravity alone, making use of the counterweight principle. The enormous tubs, called caissons, measure almost 43m (140 feet) by 10m (33 feet) and they hold more than 1 million litres of water, weighing more than 1 million kg (2,200,000 lbs). The heavier caisson lowers to raise the lighter one.The caisson that rises is set to stop 30cm from the canal water level at the top. The raised caisson then opens at the gate to allow more water in. The boat in the caisson can sail out. The lowered caisson is opened to release water, making it now the lighter one. The gates are closed and gravity can force the upper caisson down and raise the lower, and now lighter one up. By manipulating the flow of water, the weights in the caissons can be changed.

This is one of 44 locks in the 386 km (240 mile) canal system, known as the Trent-Severn Waterway. It connects many lakes and rivers to allow boats to travel from the Bay of Quinte to Georgian Bay. The water system has been used for military purposes and cargo shipping, and now it is a major tourist draw for cottage country in Ontario. Over the length of the waterway, it raises boats an incredible 180m (591 feet).

The history of the construction is as fascinating as the function of the lock. It is a true marvel of engineering and ingenuity. It is no wonder that the opening in 1904 drew a crowd of thousands to see it operate for the first time.
It is also not surprising that the lift lock has been deemed a National Heritage Site.