Washington ? For all the talks interpretive guide Nick Racine has given to visitors about this volcano, standing on the crater rim and watching as the mountain pumps out tons of rock in its own rebirth left him nearly speechless.

“Holy cow, it’s incredible,” said Racine, who is normally assigned to the Johnston Ridge Observatory on the other side of the volcano. “It’s hard to describe.”

Racine joined a group of rangers, scientists and journalists in a five-hour ascent of 8,363-foot Mount St. Helens on Thursday, about a week before the crater rim is scheduled to be opened to climbers for the first time since the mountain began quietly erupting in 2004.

Dust, steam and blue-tinted sulfurous gas rose from the horseshoe-shaped crater left by St. Helens’ 1980 eruption, which killed 57 people and blasted more than 1,300 feet off the peak. Near the crater’s center, the volcano is rebuilding itself, churning out a cubic yard of rock per second – a rate that could see the volcano return to its pre-1980 size in 100 years.

As the cooled lava reached the top of the bulging dome, it fractured and fell in rock avalanches that sounded like crashing glass. The region’s intact volcanoes – Mount Rainier, Mount Adams, Mount Hood – loomed above the distant clouds, serving as a reminder of St. Helens’ once-impressive profile.

Two members of a news media climbing party sit Thursday on the crater rim of Mount St. Helens. The volcano is scheduled to reopen for climbers on a permit-only basis July 21 after being closed since volcanic activity resumed on the mountain in September 2004.

When climbing was reopened in 1987, St. Helens became one of the most popular climbs in the country, attracting about 12,000 people a year.

But in September 2004, the volcano reawakened with a near-constant drumbeat of little earthquakes. Tourists flocked to the visitor centers to witness the billowing clouds of ash and steam as the U.S. Forest Service closed trails around the mountain.

Since then, the volcano has settled into a pattern of constantly extruding lava with a low gas content, said Tom Pierson of the U.S. Geological Survey. Dissolved gas in lava is what drives most explosive eruptions, so the chances of an eruption sending rock to the crater rim appear remote.

“It’s lost its fizz,” Pierson said. “It just doesn’t contain enough gas that would make climbing dangerous.”

Still, the Forest Service cautions anyone who makes the arduous, but not technical, five-mile hike to the crater rim beginning July 21.

In addition to basic backcountry necessities such as a compass, map and plenty of water, the service recommends that climbers bring an ice ax, sunglasses that seal around the eyes to keep dust out, a dust mask and a climbing helmet, just in case the volcano sends rocks soaring above the rim.

The entire south side of the mountain is being reopened to climbers, as are trails through the blast zone on the north side. The crater itself remains off-limits.

Permits are required to hike above tree line and cost $22 each. The Forest Service will issue up to 100 permits a day, and reservations can be made on the Internet through the Mount St. Helens Institute.

The most popular climbing route begins on the south side at Climber’s Bivouac, elevation 3,800 feet.

When climbers reach the narrow rim and look into the 1.2-mile-wide crater, the ascent’s difficulty is quickly forgotten – especially when they consider that nearly everything they see on the floor 2,000 feet below has built up since 2004.

“Everything in our perspective here is new. It’s all been erupted over the last year and a half,” said Peter Frenzen, a St. Helens specialist with the Forest Service, as he gazed into the crater. “Everything we’re standing on is less than 3,000 years old, so we shouldn’t be surprised that this thing can pump out rock.”