Although the majestic rumble of the falls can be heard from miles sway, there is no preparation for the sight itself; a great arc of hissing, frothing water crashing over a 52m cliff amid dense clouds of drifting spray. This spume of spray lifts high into the air as the dark green waters of the Niagara River thunder into the cauldron at the base of the falls.

There are two parts to this famous waterfall: the American Falls and the Horseshoe Falls. Between them is Goat Island, a tree-covered islet that sits in the middle of the river.

The Horseshoe Falls, some 800 meters wide on the Canadian side of the border, are perhaps the better known of the two. A road beside the river gives a good view of the falls at very close range, where the surface of the water has the appearance of dark green glass, turning to foaming white as it slides over the cliffs. On the Canadian side the Skylon and Minolta towers offers panoramic views of the whole area. It is also open at night to enjoy the floodlit waters.

An elevator from the Horseshoe Falls leads to the Journey behind the Falls, where a series of rocky tunnels take visitors behind a wall of water, where the noise from the crashing waters is deafening, and so thick it blocks out daylight.

The American Falls are smaller and have piles of broken rocks at their base, as opposed to the sheer plunge of the Horseshoe Falls. The sheer power and size of Niagara is best seen from the boats that brave the churning waters beneath the falls. Stunning close-up views of the falls are available from the vantage point of the Maid of the Mist.

Bridges and parks on both sides of the river provide good vantage points. One of the most popular is Rainbow Bridge, named after the rainbows that shimmer in the spray above the falls.

Originally the river dropped over an escarpment about 11km north of the present falls, but as the softer rocks underneath the dolomite were eroded by the fast-flowing water, the dolomite collapsed. Bit by bit the waterfall retreated, so that the falls today are a far way from where they were 10 000 years ago, and in their retreat they have left behind a deep gorge. The falls moved back at a rate of about 1m per year.