IN 1942, when he was 19 years old, Yale junior Eliot DuBois headed West to run the Middle Fork of the Salmon River in a folding kayak. He and his three companions hoped for one last whitewater fling before World War II overtook them, but for DuBois, at least, the Middle Fork proved to be a more memorable experience than the Marines.

A wild mountain tributary of the Snake River which cuts through a series of tortuous canyons near Sun Valley, Idaho, the Middle Fork of the Salmon is as difficult and dangerous as any river in America. It was at flood stage when DuBois and company arrived that June, but they started out anyway. Almost immediately they ran into trouble. One person's boat overturned, and although he was able to swim to shore safely, his boat was utterly smashed.

By the time the young adventurers finally made their way to a road, three of them had lost their taste for the Middle Fork. DuBois, however, wanted to keep going. After listening to his reasons, one friend summed up the sentiments of the rest when he said, "I think you're nuts, just plain nuts."

"Granted," DuBois replied, "but this is what I want to do."

Thus began the first solo run of the Middle Fork in a kayak, which DuBois recounts in his charming memoir, An Innocent on the Middle Fork; A Whitewater Adventure in Idaho's Wilderness. Although he was the best kayaker among his friends and a future U.S. whitewater salmon champion, DuBois had never before encountered anything like the Middle Fork at flood.

Using all the strength, guile and luck he could muster, he flew unscathed amid the boulders for nearly a week until he finally rolled in Impassable Canyon. Warned that there was no way out of the canyon on foot, he swam desperately for his boat, climbed up on the overturned bottom, and paddled it upside-down through the next stretch. Ever the innocent optimist, DuBois thought he had the river licked at this point, but it just proved to be the prelude to the climax in "the beast at the bottom of the canyon."

DuBois does not write as well about whitewater as William H. Calvin or Dean Krankel II, whose respective books The River That Flowed Uphill and Downriver appeared recently, but by the end it is hard not to admire young DuBois or the river that has since become an international mecca for whitewater enthusiasts.

ONE OF the most encouraging developments in American letters over the last few years has been the emergence of a group of strong, regionally rooted essayists. The trend has been perhaps most evident in the West, where Kim Stafford's Having Everything Right recently won a Western States Art Foundation Award and Robert Michael Pyle's Wintergreen recently won the Burroughs Award.

Now Charles Bowden's Frog Mountain Blues has arrived to join this vital company. Like Stafford and Pyle, Bowden is committed to protecting the land he knows and loves -- in this case, the Santa Catalina Mountains near Tucson -- from ravages of "the zany urban throngs . . . greed fiends . . . real estate developers . . . and used car salesmen."

Bowden's method in Frog Mountain Blues is to weave evocations of his rambles in an ecologically remarkable wilderness with profiles of the old characters who still remember what the mountains and Tucson were like before the Sunbelt onslaught. The result is a personal and provocative work that entertains at almost every turn in the trail, as when Bowden encounters Buster Bailey, a pioneer Santa Catalinas cowboy who "is hell on weak whiskey," backpackers and the general thrust of late 20th-century civilization.

"Up on the mountain, there is a Buster Springs and above Buster Springs rolls Buster Mountain. For the old man this seems a trifle strange. He is Buster Bailey, seventy some years old, a man living in a junkyard with a household bagged at the dump. In a city of half a million, he is a ghost." Bowden finds him, though, and initiates a relationship that is remarkable, among other things, for his and the old man's ability to disagree.

Illustrated with stunning color photographs of the Santa Catalinas by Pulitzer prize-winning photographer Jack Dykinga, Frog Mountain Blues makes an attractive -- and effective -- plea for wilderness preservation that is reminiscent of John Nichols' If Mountains Die.

THIS IS a curious book with an unusual history. Originally written a half century ago, it represents an old man's effort to set down some of the tales gleaned from a long and active sailing career on Massachusetts' Buzzards Bay. The stories were never intended for anyone outside the family, but after Edward Weeks published one about an old-style Cape Cod clam bake in The Atlantic, their audience expanded considerably. Finally, Llewellyn Howland's Tales of a Grandfather were collected and published by Harvard University Press under the title Sou'West and By West of Cape Cod in 1947.

Reissued on the 40th anniversary of its first appearance, the book is an account of growing up sailing in a New Bedford Brahmin family around the turn of the century. At best, it combines strong characters (such as the Marlow-like Skipper) with dramatic marine action.

Problems arise with Sou'West and By West of Cape Cod from several quarters, though. Howland is so intent on bringing back the world of his youth that he sometimes drowns it in a wash of irrelevant detail, as when he specifies that certain generous slices of bacon were five-eighths of an inch thick.

More troubling are the contradictions and gaps in Howland's romanticized picture of upper-class Buzzards Bay society. He lauds family and nature without apparently realizing the tremendous damage his family's business activities did to sperm whales. Similarly, he is seriously afflicted with what Benita Eisler recently described as the "the voluptuous thrift of the very rich." He glories in the simple, semisubsistence life of the shore farm without apparently realizing how his family's factories were part of an industrial process that destroyed that life for the average person.

But put him at sea, with a lively wind at his back and a responsive boat beneath him, and Howland can run with almost anyone. Like the prototype of the famous Concordia class yawl his son built for him in 1940, Howland's waterborn tales display classic lines that will delight sailors today as much as they did when they first appeared.

IT IS HARD to imagine a more congenial companion for a tour of East Coast wildlife than Ted Levin in Backtracking: The Way of a Naturalist. From the drainage sumps of Massapequa to the mountains of Vermont, Levin is consistently entertaining on subjects as diverse as the Batesian mimicry of red-backed salamanders to the ways freeways have encouraged the return of Eastern coyotes.

Recounting how something startled an owl a friend once brought to school, Levin notes, "the horned owl suddenly tightened its grip, setting all eight talons in his arm. He left the school, the owl fastened to his arm, and drove to the nearest hospital. The bird had to be anesthetized before its talons could be pried from his arm."

A fine dry-land companion to George Reiger's Wanderer on My Native Shore, Backtracking breathes with the sort of nature writing that awakens the reader to the world around him -- be it the Mandelbaums' backyard or the River of Grass.

Bruce Brown is the author of "Mountain in the Clouds: A Search for the Wild Salmon" and is at work on a book about the American farm crisis.