WHERE: Oneonta Gorge, a narrow chasm within the Pacific Northwest's Columbia River Gorge.

WHAT'S THERE: A hidden world where sheer cliff walls loom overhead, and underfoot the Oneonta creek bed spans the distance between the canyon walls.

WHAT ELSE: Unique aquatic and woodland plants. Oneonta's mossy basalt cliffs are home to ferns, mosses, hepatics and lichens, many of which grow only in the Columbia River Gorge.

Former Advertiser reporter and hiking enthusiast Tom Kaser sent this nugget from his recent hike there: "Slot-like Oneonta Gorge is a spectacular yet relatively little-known hike accessible only from the Historic Columbia Gorge Highway," he wrote.

"Spring and early summer brings too much fast flowing water through the narrow canyon, but in late summer and early fall you can walk it in shorts and water shoes," he said.

"At the end of the half-mile chasm is a stunning 100-foot waterfall and pool. Depending on how long you tarry — why rush? — you can hike in to Oneonta Falls and back out in an hour or two," said Kaser.

TIP: Adequate footwear is essential to walk the gorge. "Sometimes you're walking on pebbles; sometimes you're waist high in (very) cold water; sometimes you're scrambling over large logjams," Kaser said. For those who prefer to keep their feet dry, the 2.7-mile Oneonta loop trail takes hikers on a route above the canyon.

IN THE AREA: The Columbia River Gorge stretches more than 80 miles through the Cascade Range, forming the boundary between Washington state to the north and Oregon to the south. In 1805, the gorge's river route was used by the Lewis and Clark Expedition to reach the Pacific.

Access to the Oneonta gorge is from the Historic Columbia Gorge Highway, a 70-mile scenic route that crosses the area's many bridges and waterfalls. Less than two miles from Oneonta Gorge is Multnomah Falls, which drop 620 feet, the second-tallest year-round waterfall in the nation.

GETTING THERE: Drive Interstate 84 east of Portland 35 miles to exit 35 and follow the Historic Columbia Gorge Highway scenic route 1.5 miles back to the large Horsetail Falls Trailhead parking area.