Niagara Falls is about as deep as it is tall: the water in the river immediately below the main falls is roughly 170 feet (about 52 metres) deep on average. This deep “plunge pool” sits at the base of the Horseshoe and American Falls, carved out by thousands of years of erosion.

The actual drop of the Canadian Horseshoe Falls is around 57 metres (about 188 feet) from crest to river level. The plunge pool beneath the main falls is typically described as about 35 metres (around 100 feet) deep, with the deepest section of the river just downstream reaching about 52 metres (170 feet).