"Whatever you do," our guide Steven cautioned, "do not run if a gorilla charges you."

I was standing with three other trekkers at the Ugandan Wildlife Authority office in Bwindi Impenetrable Forest National Park. It was 8:20am and Steven was delivering his briefing before we went to track the mountain gorillas.

"If you run, the gorilla will know that you're a coward, and he'll chase you."

"What happens if he catches you?" I asked.

"Just don't run," Steven replied.

I tried to envision myself staying calm during a charge. Ideally, you're supposed to crouch down and avert your eyes, showing the gorilla respect. I couldn't picture it. I could only picture a lot of screaming and running. I took a deep breath.

our group in total

Steven ran through the rest of the trekking rules (don't go if you're sick, maintain a 7 meter distance, no flash photography, don't eat or drink around them, one hour time limit) and then the other trekkers (a New Zealander and a British couple) and I piled into a Landcruiser. Our entourage (Steven, a porter, and three soldiers from the Ugandan Army) rode up on the roof rack.

We began our trek from a village outside of the park. Here the mountains were almost completely stripped of forest, instead covered in lush crops: banana, coffee, tea, and avocado. It was a clear sunny morning and the sun sliced through the morning chill (it was 15°C [59°F] in my banda, or traditional African hut, when I woke in the morning – not what you expect in equatorial Africa).

After a brisk hike up the village hills we entered the actual park. The transition was abrupt and stunning. Here were wild, untouched jungle mountains, solid green blankets of trees. As we entered the park the forest canopy shaded and cooled us. We walked on a narrow path that wound up and down the mountain slopes, over enormous fallen trees that sometimes gave way beneath my feet like soil. A rainforest makes quick work of decomposition.

Once we'd entered the park Steven got on the radio and communicated with still more members of our entourage. The two trackers had been in the jungle since early morning, following the gorillas' route from where they'd slept the night before.

trekking through the bush

After 30 minutes we found the spot where the trackers had left the main path and hacked their way into the bush. We followed their narrow path through extremely thick vegetation. Deep piles of fallen leaves and compost made the forest floor springy to walk on. Thorn bushes and twisting vines caught my legs. I crawled under giant cascading ferns and wild, sprawling undergrowth. Occasionally we'd tromp through an ant colony; they'd march right up my shoes and socks, under my trousers, and make their way up to my boxer shorts before biting. The huge, godforsaken soldier ants (also known as "suture" ants because their powerful pinchers can literally be used to suture wounds) drew blood.

Finally we came to a flat, open area in the jungle, about 5m (16ft) in diameter. "This is where the gorillas slept last night," Steven told us. We all studied the area with a new interest and excitement. I noticed six distinct impressions in the leaves, nests made by massive creatures. More amazing was the sheer scale of the clearing. Ten 200-500lb beasts can really bulldoze an area of forest when they choose to.

Steven had been communicating with the trackers and had some news: we'd have to walk further than expected. Our group of gorillas had apparently clashed with a wild group of gorillas earlier that morning and had run off into the hills.

The group of gorillas we were seeing, called Mubare, or the M group, was the first group to be habituated in Bwindi. There are now four habituated groups, although one is exclusively reserved for researchers. The habituation process takes two years. During habituation, park rangers make daily contact with the gorillas. The rangers must be both experienced and brave, as wild gorillas are frightened of human beings and frequently charge. After habituation the gorillas grow accustomed to seeing human faces everyday for about an hour. They're still in their natural habitat, but an element of wildness has left them. They no longer consort with the truly wild gorillas; encounters send them sprinting.

We resigned ourselves for a long walk through the jungle, following the gorilla paths that the trackers had broadened with machetes. Great mounds of gorilla dung lined the path at irregular intervals. Our journey took us straight uphill.

Sooner than expected, some news shot through the ranks: we'd encountered the trackers.

Ian, the Kiwi guy ahead of me, gave me a thumbs up.

Then I heard it: a low rumble like a deep, prolonged snore.

We were right on top of the gorillas! I continued walking and then suddenly noticed a bit of black amongst the green. It was the crest of a gorilla's head.

Our group assembled in a small clearing and prepared for our visit. We had our last sips of water, got our cameras ready, and set down our bags and walking sticks (big sticks freak the gorillas out, supposedly conjuring up memories of hunters).

juvenile gorilla

As we turned to walk toward M Group I made my first real gorilla sighting: a baby and a juvenile playing in some bushes. Then I heard a great crashing and snapping of branches behind me. I was seized with panic; my shirtfront thumped in and out with my heartbeat. I looked back. Two female gorillas were feeding peacefully in the trees.

We crept toward the baby and the juvenile. They glanced at us and continued to bounce on the branches. As we neared them, a giant reclining figure came into view – the silverback! He was dead asleep, letting out tremendous, irregular snores.

The juvenile and baby continued to play. They were almost obscenely adorable. The little guy swung around the branches, leapt on his older brother, and then scampered away, beating his chest just like they do in the movies.

the silverback withdraws

The noise of our advancement soon woke the silverback up. He shot us a quick mistrustful glance before rolling over onto all fours and walking away. As he did, he made a barking gargle. This, Steven informed us, was a call for the rest of the group to follow him, which they promptly obeyed.

We waited for a minute in the clearing. Steven told us that the silverback was likely still shaken from his morning encounter with the wild gorillas. We then pursued the group.

The silverback was sitting in a small clearing, plucking leaves off bushes and chewing them gingerly. He watched us watch him. We crept a bit closer. He rolled over to all fours and tromped away.

Unperturbed, we followed right after him. I felt a bit guilty about bugging the big guy, but I was also drunk with excitement and joy and photo-lust, and so followed Steven and the others.

mamma gorilla

The rest of M Group sat in clusters in a small open area. The silverback sat with a female beneath an enclosed area of bushes. A tiny, one-year old infant clung to the female. The silverback looked our way and, exasperated, dropped to the ground and fell fast asleep.

The other members of the group climbed in trees and ate leaves and groomed each other. We observed them and took photos for about 30 minutes.

The silverback woke and began feeding again. Now he looked at us with acceptance and tranquility. He even crawled into the clearing, took a seat, and fed; as he did so he came within three meters (10 feet) of me. Adrenaline pumped through my body, but I wasn't afraid in the least. I was at peace, in comfortable awe of these beautiful giants.

(awww!) two-year-old gorilla

The two-year-old baby climbed down a tree and began advancing toward me. He was curious about the gleaming aluminum legs of my tripod. He came a little too near and Steven shooed him away. He sat back for a moment and watched us, then advanced toward the tripod once again. Finally, after four attempts, Steven said, "Okay, let him touch it," and the baby ape cautiously came forward – just a meter from my feet – and ran his hand across the lower leg of the tripod. Satisfied, he scampered back to play with his siblings.

This was all done under the watchful eye of the silverback.

"One minute left," Steven said.

I was stunned. One minute? It felt like we'd only been there for one minute.

There is only one mountain gorilla for every 10 million people on earth

We waved our goodbyes to the silverback. As if sensing our departure, he advanced toward us and gave us a final, full-frontal photo op.

We sliced a new path down the mountains. The visit was over. After we'd walked a sufficient distance from the troop, we sat in a small dry clearing and ate our packed lunches. Everyone was silent and grinning. I felt about as happy as I've ever been in my life. It had been a great day.