The Ottawa River, La Rivière des Outaouais, starts out deep in chain of lakes in the Laurentian Highlands and passes through minimal civilisation for most of its 1270 length before it passes through the City of Ottawa, and eventually merges with the Saint Lawrence at Montreal. Quyon, where the first ferry crosses, is already within commuting distance of the City of Ottawa.

Upstream of Quyon the river narrows enough for the occasional bridge, and the population density is not sufficient to support the cost of ferries.

The Ottawa watershed is the home of the Algonquin people. In colonial times it became an important canoe route for trappers and for trade, and later for the export of lumber.

Now very little trade goes along the river, its main uses being hydro-electric power generation and recreational boating— there is a popular circuit from Kingston up the Rideau Canal to the City of Ottawa, down the Ottawa River to Montreal and then back to Kingston on the Saint Lawrence.

The Saint Lawrence River, Le fleuve Saint-Laurent, drains Lake Ontario and hence all of the great lakes. It officially starts at Kingston and forms the Thousand Islands as it cuts through the Frontenac Arch, a hard strip of Precambrian rock that links the Canadian Shield to the Adirondacks. Several public ferries link the larger islands, but most of the smaller ones are privately owned with no public access. The easiest way of seeing more of the islands is by one of the many Thousand Island cruises operated from the nearby towns.

Continuing downstream there are currently no more ferries before the Montreal area. Several major bridges provide adequate crossing places. Other ferries have existed here in the past, and there is pressure to re-introduce them in some places. But much of this section of the river forms the border between Canada and the US, and that complicates setting up more ferry crossings.

The Hochela Archipelago is the name, little used it seems, given to the collection of islands around Montreal that mark the merger of the Ottawa into the Saint Lawrence. There are about 30 road, rail and foot bridges and tunnels that connect these islands to the mainland and to each other. The big city warrants big answers to its transport needs, and so ferries occupy only a tiny niche. Unlike many major cities built around water, Montreal has no commuter ferry services. Where there might be a market the unreliability of winter ice would probably rule them out.

This is a big, powerful section of the river, with a steady traffic of large cargo vessels and the occasional cruise ship serving the Port of Montreal and, via the Seaway, all the ports of the Great Lakes.

Downstream from Montreal it widens into the shallow Lac Saint-Pierre. By Quebec City it has become tidal. And after passing Île-d'Orléans it gets steadily wider, so that by the time the Saguenay joins, it is 25 wide and feels like the sea, no longer like a river. No way can bridges or tunnels serve this area; here the ferry is king.

We once made the drive from Tadoussac along the North Shore as far as Forestville before turning back. But Hwy 138 continues a long way east, through small towns like Baie-Comeau and Sept-Îles, before it also eventually gives up. After that you can fly, you can ski-doo on the ice road in winter, or you can take a ferry.

This is terra incognita most people including me. But it is also home to small communities based around fishing or other resources, and they need the ferry services to keep them connected to the modern world.

Compared to the North Shore the land around the southern Gulf of Saint Lawrence is somewhat more hospitable. Most of the ferries running here work to schedules of several times a day, rather than once a week. Nova Scotia, Prince Edward Island, Newfoundland and the Magdalen Islands attract summer tourists, and the ferries make fun alternatives to bridges or flying.

But storms and winter ice conditions are unpredictable and often severe. This is still a tough environment that sees many service cancellations and the occasional call for help from coastguard ice breakers.