Where the St. Lawrence River tumbles out of Lake Ontario on the US/Canada border, an archipelago of over 1,800 granite islands litters the waterway, creating a beautifully scenic landscape. Windswept and draped with native pines, the islands are home to opulent historic mansions, whose turrets jut above the treeline, and luxurious cottages and estates, which are the present-day retreats of the Canadian elite. One particular landmark is the slightly incongruous Boldt Castle, a six-storey, 120-room Rhineland-style structure that resides over Heart Island, a common photo stop on the various boat tours that weave through the waters.

This area is also a busy marine highway, and the secluded bays once provided the ideal hiding place for villains and vagabonds running from the law or trying to sneak across the international border. However, the geography creates a natural obstacle course with its many rocks and shoals, and so a number of passenger boats, paddle steamers, and freighters have come to a watery end on these straits, making it one of the best freshwater shipwreck diving destinations in the world.

The two main towns that top and tail the seaway here are Kingston and Gananoque. Each has its own charm and interesting heritage — indeed, Kingston was once the capital of the ‘United Provinces of Canada’ until that title was moved to Ottawa — and either is well placed as a stopping-off point for those travelling between Toronto and Ottawa or Montreal.