''Everyone follow right behind me, stick together or else you'll get lost," volcanologist Victor Okrugin shouted above the roar of the nearby stream. "Most of all, watch out for the boiling mud pots."
No one in our little group needed any further urging. Here we were, passing through a narrow canyon cut by the river through the rim of an active volcano while misty skies and a persistent drizzle cut visibility to a minimum.
There was no question but to follow Mr. Okrugin, one of Russia's leading experts on volcanos, as he led the way, pack on his back, kerchief tied around his head, and walking stick in hand.
After a few more minutes of struggling along in the crumbly volcanic ground, another world unfolded: a cacophony of sights and sounds straight from the bowels of the earth.
To the right was a protruding natural vent, roaring like a jet engine as chalk-white steam gushed out at tremendous pressure. To the left was an enormous cauldron of boiling gray mud, seething and gurgling as giant bubbles broke the surface.
On a small hill just beyond, an opening in the ground was covered in yellow and hissing - the source of the acrid sulfurous smell that permeated the air. Behind it a geyser shot streams of hot water up into the fog.
The cascading river cut straight through the scene, the product of melt from a glacier that hugged the bottom of the steep red canyon walls far above.
Dante's inferno? No, this was inside Mutnovsky Volcano, just one of 29 active volcanos (out of over 100 in all) on Russia's mighty Kamchatka Peninsula off its Pacific coast.
Because of the opening through the rim, it is considered the most accessible for a visit.
But only barely. Just getting to the starting point of the final hike involved a slow, bumpy ride in a huge truck over snowfields and barren volcanic rock slides, skirting around another active volcano that last erupted just a few years ago.
A new frontier
A trip to Kamchatka is not for those unwilling to put up with certain rigors. It is still a real "frontier," a place that even few Russians have ever had the chance to experience.
It's also only been a few years that foreigners have had any access at all, primarily due to a nuclear submarine base located near the peninsula's only city, Petropavlovsk-Kamchatskiy, which straddles one of the finest natural harbors in the world.
The Soviet government also considered the peninsula far too strategic because of its geographic location as Russia's eastern-most border, sticking down into the Pacific Ocean like a giant thumb pointed at Japan.
But as with other formerly off-limits parts of the ex-Soviet Union, since 1991 Kamchatka has become an increasingly favorite destination for adventure travelers, volcanologists, and bear specialists - this because of its huge population of large brown bears, cousins of the North American grizzlies.
It has also become the focus of attention for environmentalists because of threats to its fragile ecosystem, such as the overfishing of its famous king crab and plans to begin gold mining operations that could destroy salmon spawning grounds.
Our group was on a trip organized by the environmental group Friends of the Earth to inspect such potential problem areas. Sadly, not far from the Mutnovsky crater, seepage from two abandoned gold mines continues to run into a nearby river.
Most of the peninsula, however, is so remote that it remains untouched. Almost all key locations can only be reached by helicopter, making a visit both expensive and difficult to arrange.
There is only one major road, that runs for over 375 miles up the central valley, and most of it remains unpaved.
The valley is characterized by deciduous and conifer forests, meandering rivers, and, in a few places, farmland.
Yet it is the volcanos that most characterize the peninsula, formed by two parallel chains that run north/south along most of its length.
Part of the Pacific "ring of fire," Kamchatka has more volcanic activity in its relatively small area than anywhere else in the world.
In the north rises the tallest active volcano on the Eurasian land mass, mighty Mt. Klyuchevskoy; it is so active that its altitude changes almost constantly (currently around 15,000 feet). All this activity is because of the mountain's geographic position where the Kuril and Aleutian chains of volcanos meet. In fact, the end of Alaska's Aleutian Island chain lies not far offshore in the Commander Islands, named for explorer Vitus Bering.
Volcano erupts - even now
Mt. Klyuchevskoy is hardly alone. Many other volcanos have erupted in recent decades, in some cases violently. The latest large-scale eruption occurred in early January this year, when a volcano known as Mt. Karymsky caused such uplift that a nearby lake half vanished.
That former lake bed is now firm enough for helicopters to land on, where the gray, dusty soil is still very hot.
Just a short distance away, the near-perfect Karymsky cone continues to eject gigantic black and white clouds of ash and steam, followed by strong rumbling sounds; it is a spectacle that repeats itself every 15 minutes or so.
"This is rather unusual activity for a volcano, to have it behave like this with such regularity," says volcanologist Yevgeny Vakin, who ambled over to greet our group after the helicopter set down. Vakin was spending the summer in the area, doing what those in his trade do: Stay near enough to observe, take water and rock samples, but also know when to back away.
While interesting to observe from the ground and from within, the volcanos are equally dramatic when viewed from the air. Every glance out one of the Russian MI-8 helicopter's round portholes reveals a different peak, ridged cones with wide fingers of snow cascading down their sides towards the valleys below.
One mountain has a charming crater lake at its summit, its steaming water a turquoise blue.
Another has a larger, cold-water lake within an enormous caldera (a volcano whose cone has collapsed in on itself, allowing such lakes to form and forests to regrow).
Valley of the Geysers
Perhaps the most unique destination of all is the Valley of the Geysers, a narrow, vegetation-covered canyon that features scores of big, small, and in-between geysers and mud pots.
The thermal water hosts myriad "thermophile" microorganisms and bacteria, forming a multicolored backdrop to the clouds of steam that rise up from the valley floor.
As in Wyoming's Yellowstone Park, most of the geysers spout with systematic regularity, shooting out steam and boiling water up to differing heights.
The largest, known as Velikan (or Giant), is Kamchatka's version of Old Faithful; its eruption can reach up to 170 feet high. In addition, there are myriad mud pots, consisting of thick muck that makes deep belching sounds as volcanic gases break the surface.
International adventure travel agencies can now fly to Russia's Kamchatka Peninsula direct from the United States' West Coast via Anchorage.
Located nine time zones east of Moscow, geographically the peninsula is closer to the Americas than it is to the Russian capital.
Accessible by helicopter
The growing travel trade has sparked certain controversy, the same dilemma faced by innumerable other wilderness areas by the issue of how best to preserve the fragile ecosystem while helping boost the local economy through tourism.
At present, certain areas are only accessible for helicopter day trips, while others remain open only to scientists and other specialists.
The local company, however, that controls the fleet of helicopters now has plans to build a new hotel and visitor center in the Valley of the Geysers, something local scientists see as leading to disaster.
"We're not against tourism, far from it, but there must be strict control at the same time," says Vitaly Nikolaenko, a naturalist and bear expert who has served as park ranger in the Valley of the Geysers for 25 years. "Otherwise, what you see here will be in great danger."
He pointed off into the distance along the S-curved valley, its multi-colored rocks and vegetation partly obscured by clouds of steam wafting up from scores of geysers all along its length.
Currently, the valley is one of seven parts of Kamchatka Peninsula being considered by UNESCO for designation as World Heritage Sites, because of their unique character.
Environmental groups also oppose plans for new gold mining, that could have a major impact on indigenous peoples, in particular Itelmens who live along the peninsula's east coast in tiny fishing villages.
It is a debate unlikely to be resolved anytime soon.
In the meantime, a small number of specialists and adventuresome travelers will continue to visit what is arguably one of Russia's - and the world's - most remarkable natural wonders.