Peterborough Lift LockPeterborough Lift Lock, Trent-Severn Waterway, Ontario, Canada. Unreinforced concrete towers support two caissons filled with water that are used to raise and lower boats 19.8 meters (65 feet). The caissons, or lock chambers are raised and lowered by a ram, or hydraulic cylinder. This is the highest hydraulic boat lift in the world, and one of only 8 of its type. It was built of unreinforced concrete, and opened in 1904. It is still in full operation from spring until autumn.This image is copyright and may not be used without specific authorization. Permission is explicitly denied for Pinterest.