At the front of the line, reserved for those who risk falling behind and getting lost in the endless shadowy sea of green bamboo, an Australian woman asks, "How long until we find them?"

"Soon," our guide replies, patiently answering her question for the fifth time since we started hiking two hours ago. "You need rest?"

She nods, out of breath, and we stand in the rain long enough for the sweat under my sodden fleece to turn cold. Nobody says a word. I try not to glare at our weakest link, instead taking a moment to look around Rwanda's Parc National des Volcanes.

Nothing but mist, bamboo, and the white noise of rain falling on leaves 10 metres above. I glance back at the soldier bringing up the rear, water dripping off the barrel of his AK-47. He's clearly not impressed.

Our guide's radio crackles with news from the trackers.

"They are there but not happy," he frets. "They are like people. Don't like rain."

They are Central Africa's rare mountain gorillas. Scattered throughout the volcanic range shared by Rwanda, Uganda, and the Democratic Republic of Congo, only about 700 gorillas roam the mountain forests in families of 10 to 34. The revenue generated from gorilla tourism is significant, to the extent that the Rwandan government has appointed an elite military unit to guard the park, its visitors, and the gorillas themselves from incursions by rebels based in the Congo. At a cost of US$375 per person, it's a high price for a maximum of an hour spent with the gorillas. Yet treks are almost always full–many view gorilla tracking as one of the premier wildlife encounters on the planet.

Soaked through and shivering with cold, we march for another half-hour until the bamboo is replaced by lush rain forest.

"They're here," our guide whispers. He instructs us to leave everything but our cameras under a tree. "Follow me."

Ducking through a tangle of vines and branches, we break into a small clearing. The two trekkers in front of me freeze, and it takes only a moment for me to follow suit. A 160-kilogram male silverback gorilla sits to our left, chewing bamboo. He glances at us, indifferent.

A few metres away, an even larger silverback turns toward us. Standing to a full height of six feet, he takes a few steps in our direction, slapping his chest in a thumping declaration of superiority.

"No. 1," the guide explains quietly, smiling at our wide-eyed alarm. "The boss."

Remarkably, the rain has stopped and the gorillas are basking in the dry, warm air. They are everywhere–eating, wrestling, cartwheeling, spinning, climbing. "Our friends are drunk," the guide chuckles. "Too much bamboo." Two-year-old twins, the only pair of its kind in the world, tussle with an older cousin. An eight-month-old clings to its mother's back. Clowning on a log, an adult female rolls her eyes and poses, as though for a fashion magazine spread.

We've been instructed never to touch the gorillas and always to stay at least seven metres away to prevent transmission of human diseases, but on this day the rule is not strictly enforced. The guide doesn't prevent the gorillas from approaching of their own accord to as close as two metres, when he finally steps in and directs us to back slowly away.

There is little the guide can do when a gorilla decides to move quickly and a human being is in its path, however. At one point a cavorting toddler runs into my leg. A few moments later, as I'm kneeling to take a photograph, the guide puts a firm hand on my shoulder and urges me to move. I drop my camera to discover that No. 1 is passing a metre in front of me, his hulking form close enough to touch. We make eye contact, the gaze of an assured, indifferent monarch meeting that of an awed subordinate. I marvel at the closeness of our encounter–no bars, no glass, no railings–and back away, head bowed. The guide has assured us that attacks on human visitors are rare, that the occasional bluff charge from one of the protective dominant males is a heart-stopping but harmless show of aggression. Eye to eye with this powerful primate, I'm grateful for his wary tolerance of my presence. In the event he decides I'm not wanted, I know I wouldn't stand a chance.

The hour passes quickly, magically. At the end our eyes are still wide and we don't want to leave. "I would pay $2,000 for this," a companion chuckles, shaking his head. The Australian woman chirps her agreement. We stand for a moment with the trackers and soldiers, sharing crackers and grinning like fools. Even the soldiers manage reluctant smiles. The rain begins to pour down, but we hardly notice. Returning the way we came, we descend into the mist with stories already spilling out under the bamboo forest.

ACCESS: The Office Rwandaise du Tourisme et des Parcs Nationaux ( www.rwandatourism.com/ ) operates gorilla-tracking tours every day of the year from its headquarters outside of Ruhengeri, with up to 56 permits available each day from its office in Kigali or Ruhengeri. There is a maximum of eight people per group, and flash photography is prohibited. Permits are best booked well ahead of time; peak season is July to August and December to January. A note on security: the last rebel attack on gorilla trekkers occurred in Uganda in 1999, resulting in the death of eight tourists. Rwanda has had no incidents since it reopened the park to visitors later that year.