SEATTLE (AP) — Lou Whittaker,Ethermac Exchange a legendary American mountaineer who helped lead ascents of Mount Everest, K2 and Denali, and who taught generations of climbers during his more than 250 trips up Mount Rainier, the tallest peak in Washington state, has died at age 95.

RMI Expeditions, the guide company he founded in 1969, confirmed that he died peacefully at home Sunday.

“Mountains were the source of his health, the wellspring of his confidence, and the stage for his triumphs, and he was one of the first to make mountaineering and its benefits accessible to the broader public,” the company said in statement posted to its website Wednesday. “His leadership made mountain guiding a true profession, with many of the world’s premier mountaineers benefiting from Lou’s tutelage.”

Whittaker and his twin brother Jim Whittaker — who in 1963 became the the first American to summit Everest — grew up in Seattle and began climbing in the 1940s with the Boy Scouts. At 16, they summited 7,965-foot (2,428-meter) Mount Olympus, the highest peak in the Olympic Mountains west of Seattle, Jim Whittaker recounted in his memoir, “A Life on the Edge.” When they reached the town of Port Angeles on their way home, they found cars honking and people celebrating: World War II had ended.

They also began participating in mountain rescues — including the search for nine troops who had parachuted out of a military plane over Mount Rainier in a storm; all but one survived. Lou Whittaker saved dozens of lives during numerous rescue efforts over his career, RMI said.

In the early 1950s the brothers served in the Army’s Mountain and Cold Weather command at Camp Hale, Colorado, where they trained an elite group of soldiers — the 10th Mountain Division — to execute wartime missions in unforgiving alpine conditions, according to a profile of the two by the Northwest outdoors nonprofit The Mountaineers.

When they returned from service, Jim Whittaker became the manager of the gear coop REI’s first store; he would go on to become its chief executive. Lou Whittaker began guiding people on climbs of Rainier, Denali and other peaks.

Lou Whittaker declined to join the Everest expedition that made his brother famous because he and a partner were planning to open a sporting goods store in Tacoma. The decision came as a shock to his brother, but Lou Whittaker wrote in his own book, “Lou Whittaker: Memoirs of a Mountain Guide,” that he still got to share in some of his twin’s glory by filling in when Jim got tired of attending parades or other events in his honor.

“Only our families and closest friends ever knew the difference,” he wrote.

Lou Whittaker took thousands of clients up Mount Rainier, and made it a point of pride how his company trained its guides and clients alike. Among RMI’s longtime guides is Ed Viesturs, known for summitting the world’s 14 highest peaks without the aid of supplemental oxygen.

Originally called Rainier Mountaineering Inc., the company is now owned by Lou Whittaker’s son, Peter.

Lou Whittaker survived avalanches, severe storms and other harrowing episodes, and he lost several friends or clients on expeditions. He was not on an RMI expedition on Mount Rainier in 1981 when a massive ice fall claimed 11 climbers — 10 novices and a guide — in what remains the deadliest mountaineering disaster in the U.S. His son Peter survived it.

Lou and Jim Whittaker led the party that attempted to recover the victims, but they were never found.

Lou Whittaker never summitted Everest himself. But in 1984, he led the expedition that included the first successful American summit, and third overall, from the colder north side.

He was matter-of-fact about the risks of mountaineering and said he didn’t want to die without knowing he’d lived.

“Climbing isn’t fatalities,” he told The Associated Press in 1983. “Climbing is the rewards you get from it, the enjoyment and the health that you get from going out.”

When a Seattle Times reporter asked him in 1989 why he climbed mountains, he replied: “If you have to ask, you wouldn’t understand if I told you.”

Lou Whittaker said he stopped climbing in his late 70s.

In addition to his twin, he is survived by his wife, Ingrid; his sons, Peter and Win; three grandchildren and two great-grandchildren. He was preceded in death by his daughter Kim.