OLYMPIC NATIONAL PARK — The alpine ridge between Deer Park and Obstruction Point is so grand that it’s worth hiking twice.

The 15-mile round-trip trek along Grand Ridge offers 6,700-foot views of the heart of the Olympic Mountains and holds the distinction of being the highest trail in Olympic National Park.

Some will cut the trip in half by coordinating a key swap with two parties beginning from each end of the 7.5-mile-long ridge and driving out in a different vehicle.

A lack of such planning proved fortuitous Sunday with whistling marmots outnumbering fellow hikers on an peaceful, mostly downhill return leg.

The east end of the Grand Ridge trail leaves the flanks of Blue Mountain at a 5,230-foot trailhead near the end of steep and dusty Deer Park Road.

The trail dips into a saddle and skirts the forested summit of 5,622-foot Green Mountain before it breaks into alpine meadows teeming with purple lupine.

The undulating ridge, which separates the Morse Creek and Grand Creek basins, offers an array of views from the core of the Olympic Mountains to the Sequim-Dungeness Valley.

After stopping for lunch with friends at 6,434-foot Maiden Peak, I continued solo along the ridge to a 6,000-foot saddle called Roaring Winds.

The trail climbs sharply from Roaring Winds camp to 6,773-foot Elk Mountain, the high point on the ridge.

The exposed summits of Elk Mountain and Maiden Peak are each about 100 yards off the trail and can be accessed with a quick detour.

From Elk Mountain, the ridge trail drops into a large cirque, rounding the side of 6,450-foot Obstruction Peak before it ends at the 6,120-foot Obstruction Point trailhead.

Several wilderness trails converge at Obstruction Point, which can be accessed on a white-knuckle drive from Hurricane Ridge Visitor Center.

After counting 23 vehicles at the Obstruction Point trailhead, I began the return leg at about 4:30 p.m. Sunday and passed just two other hikers for the duration of the trip.

Four Olympic marmots were spotted on the slopes of Elk Mountain, two of which announced their presence with a loud whistle.

No dogs, firearms, off-road vehicles or fires are permitted on the Grand Ridge Trail. An Olympic National Park pass is required.

For information on hiking in Olympic National Park, visit www.nps.gov/olympic.

Hikers navigate the 7.5-mile Grand Ridge trail from Deer Park to Obstruction Point in Olympic National Park. (Rob Ollikainen/Peninsula Daily News)

A marmot whistles from a rock on Elk Mountain. (Rob Ollikainen/Peninsula Daily News)