Imposing bears teem in Alaska's Katmai National Park and Preserve. But few dare enter its Valley of Ten Thousand Smokes. In 1912, a volcano was born here.

It erupted for nearly three days. Its ominous ash clouds left the town of Kodiak, 100 miles away, in profound darkness, nearly obscuring lanterns held at arms' length. The valley itself was suffocated by a gargantuan load of up to nearly 700 feet of grainy volcanic ash.

That ash remains there today. The once verdant land was transformed into a desolate moonscape. For years, potent columns of steam rose from the hot rocky ash, the "smokes" that lent the region its name.

It was the biggest volcanic eruption of the 20th century. "I'm in awe of how large that event was," Patrick Whelley, a NASA geologist, told Mashable. "What a drastic change in landscape.

" This year, Whelley co-led an expedition into the valley with a team of scientists. They investigated how this land reflects similar environments on other planets, like Mars , and the harsh, seemingly unlikely, places that might harbor life on other worlds. Such a journey isn't for the meek.

"Wind blows abrasive ash that irritates the eyes and lungs. Your food, no matter how carefully prepared, always seems to be gritty," Mike Fitz, a former Katmai ranger who often ventured into the valley, told Mashable. "Pumice and ash always threaten to get into your footwear where it can abrade your skin raw.

" Exploration of the valley has a price. But it comes with unmatched rewards. "Th.