Sailing on the Bay of Fundy

The Bay of Fundy (French: Baie de Fundy) is a bay between the Canadian provinces of New Brunswick and Nova Scotia, with a small portion touching the US state of Maine. It has an extremely high tidal range. The name is likely a corruption of the French word Fendu, meaning "split".

The tidal range in the Bay of Fundy is about 13 metres (43 ft). (The average tidal range worldwide is about one metre (3 ft 3 in).) Some tides are higher than others, depending on the position of the moon, the sun, and atmospheric conditions. Tides are semidiurnal, meaning they have two highs and two lows each day with about six hours and 13 minutes between each high and low tide.

Because of tidal resonance in the funnel-shaped bay, the tides that flow through the channel are very powerful. In one 12 hour tidal cycle, about 110,000,000,000 short tons (100 billion tonnes) of water flows in and out of the bay, which is twice as much as the combined total flow of all the rivers of the world over the same period. They are as powerful as 8,000 train engines or 25 million horses. The Annapolis Royal Generating Station, a 20 MW tidal power station on the Annapolis River upstream of Annapolis Royal, is one of the few tidal generating stations in the world, and the only one in North America.

Most of the rivers have a tidal bore, a wave front of the incoming tide that "bores" its way up a river against its normal flow. Notable ones include those on the Petticodiac, Maccan, St. Croix, and Kennetcook rivers. Before the construction of a causeway in 1968 and subsequent siltation of the river, the Petitcodiac River had one of the world's largest tidal bores, up to 2 metres (6.6 ft) high. Since the opening of the causeway gates in 2010, the bore has been coming back, and in 2013 surfers rode it a record-breaking 29 kilometres (18 mi).

Other phenomena include the Reversing Falls near the mouth of the Saint John River, a rip tide at Cape Enrage, and the Old Sow whirlpool at Passamaquoddy Bay.