With spring only weeks away, I can envision the Kenduskeag Stream and Penobscot River rolling fast, lifting white-water rafters and canoeists atop high water, through rapids, down sharp drops and along scenic shores.

But I can only envision open water. For months, as I’ve driven over bridges, the rivers below have been thick with ice, and their currents have been invisible as if these were lakes and ponds rather than flowing streams.

This winter, even saltwater coves and shoal inlets have frozen solid; cutters have worked to jiggle free boats locked in iced harbors, and the bay itself has been skimmed over on subzero mornings when the wind was still.

No telling when this particular spring there will be “ice-out.” Yet it will come and along with it will be wet-suited adventurers eager to paddle their canoes over rivers in Maine named St. Croix, Kennebec, Allagash, Carrabassett, Mattawamkeag, Androscoggin – names almost as interesting as the rivers themselves.

There is a mystique about a river that even land-lovers with their feet planted on firm ground cannot deny, a yearning perhaps, to embark on an expedition that lets the river follow its courses as the traveler is swept along.

In the journals of explorers Meriwether Lewis and William Clark, in the tales and descriptions of Mark Twain, we’ve taken our own voyages and been enchanted with the riverscapes shown to us through their words.

Such a voyage I vicariously made with William Least Heat-Moon, author of “Blue Highways” and “PrairyErth.” His latest book, “River Horse,” is a chronicle of his singular trip on American waters from sea to sea, in a 22-foot C-Dory called Nikawa, a name coined from the Osage words “ni,” river, and “kawa,” horse.

This logbook opens in New York Harbor; it closes – after covering some 5,000 watery miles – in Astoria, Ore. From the Atlantic to the Pacific, Heat-Moon recorded his historic cross-country river travels, which took him and his companions through turbulent weather, massive floods, submerged rocks and incomparable pleasures.

“I’ve driven more than a million miles over American highways,” he wrote, “but I don’t recall loving, for itself, even one road … But a river comes into existence moving, and it grows as it moves, and like a great mother carries within itself lives too varied and multitudinous for our myriad sciences even yet wholly to number and name.”

One of his passages, describing a reflective afternoon along the Ohio River, sums up his feelings:

“A river – with its attendant cascades, eddies, boils, and whirlpools – is the most expressive aspect of a natural landscape, for nothing else moves so far, so broadly, so unceasingly, so demonstrably, and nothing else is so susceptible to personification and so much at the heart of our notions about life and death.”

Those words make me impatient for open water in the Machias or in the Piscataquis, where one day I may do some scouting and paddling of my own. Or in the Saco, from East Brownfield to Hiram, which “DeLorme’s Maine Atlas” promises, “more gentle, meandering river through scenic countryside.”