I was alone in the middle of deepest, darkest Congo. Worse still, I was being chased by eight angry tribesmen in two dugout canoes – and they were gaining on me.

"Mazungu … Mazunguuu!" came the screams from behind. "Give us money!" They were all standing up and paddling like men possessed. The nearest guy had a huge machete at his waist. I had been paddling as though my life depended on it. As though? It did depend on it! The fear was rapidly growing within me, demanding an answer to the primeval question: fight or flight?

The word mazungu, white man, was being screamed and repeated along both banks. It was disconcerting, to say the least. I felt like a wolf that had inadvertently strolled into a farming community and was being hunted down. I had to go faster. But now, after paddling my heart out to the point of near exhaustion, I turned around and saw the nearest dugout canoe was less than 20m away. So close that I could see the whites of the men's eyes and their teeth bared in a contorted, hate-filled travesty of a smile. What was it going to be: roll over and expose my soft underbelly, or put up a fight? It was the venom in the next cry of "Mazungu" that made me decide. I grabbed my machete …

Thanks to winning a travelling fellowship and grant from the Winston Churchill Memorial Trust, I was on my way to making the first source to sea descent of the Congo river through the war-torn Democratic Republic of the Congo. From the true source in north-east Zambia, the Congo river is just short of 3,000 miles long and the eighth longest river in the world, with a flow rate and drainage area second only to the Amazon. It flows through savannah, swamp and dense tropical rainforest, crossing the equator twice before finally draining into the Atlantic.

The Congo has suffered horribly throughout its history, and due to generations of foreign exploitation, political instability, corruption and civil war, not to mention a prevalence of crocodiles, hippos, waterfalls and huge rapids, the river seems to have been given a wide berth. But if you're looking for a true adventure travel destination, then look no further – the Congo has it all!

Henry Morton Stanley was the first European to explore the middle and lower Congo river, in 1877. He started from Zanzibar on the Indian Ocean, and the entire journey took him 999 days. Of the original 356 men on his expedition, only 114 made it to the end. The last remaining European besides Stanley drowned on the final set of rapids, prompting Stanley to write: "I am weary, oh so weary, of this constant tale of woes and death."

congo map Photograph: Alamy/Phil Harwood

I found the proud people of the Congo to be an absolute inspiration; I believe we could all learn a great deal from their courage and resilience in the face of adversity. It has to be said however, that I also encountered my fair share of hostility too, and I don't think I've ever come as close to a nervous breakdown as I did during the five months it took me to reach the Atlantic. Collapsing unconscious from malaria didn't help.

With local help I found a tiny spring at the base of a banyan tree in the highlands of Zambia. This was the source of the most powerful river in Africa. With my five-metre Canadian canoe strapped to the back of a land cruiser, I eventually found a spot wide enough to start my trip. The upper Chambeshi was a beautiful little stream: crystal clear waters, an abundance of birdlife and lovely little rapids to keep me on my toes. The main risks were either being torn to shreds by the razor sharp thorns that seemed to come from all directions, or getting the canoe pinned against a rock or on one of the many fallen trees crossing the river. A few day's later, however, crocodiles became another consideration.

The environment had now changed, and the way became narrow and dark, with gnarled overhanging trees blotting out the sunlight. As I registering this change in mood, and my mind brought up similarities with the everglades, there was a frenetic thrashing noise to my right. Two four-metre crocodiles came crashing through the undergrowth and launched themselves off a raised bank. They were so close I remember noticing the membrane close on the nearest one's eyes. They belly-flopped onto the water with a tremendous splash and disappeared directly under my canoe, causing me to wobble in more ways than one.

Bangweulu swamp covers an area approximately the size of Derbyshire, and in 1991 was designated as a wetland of international importance. One of its biggest attractions is the lofty shoebill stork, which feeds on baby crocodiles amongst other things. At night, in the absence of firm ground, my technique would be to paddle as hard as I could and ram myself into the thickest area of reeds I could find. I'd then try to somehow drag and push my way further through, until I was securely wedged in with little risk of capsizing. I figured that since I was surrounded by tightly packed reeds, I'd have to be pretty unlucky to get a surprise visit from anything big enough to fit my head in its mouth. On more than one occasion I was awoken in the middle of the night by crashing, splashing sounds, but after a while I got used to it. Crashing, splashing sounds are one thing – something horrible ripping your leg off is quite another.

Weeks later, after negotiating the waterfalls and numerous rapids of the Luapula river, I was confronted by a wall of jungle and the river disappeared into it in a myriad of channels. In I went, and it felt like a different world. I could hear a permanent rumbling of rapids somewhere off in the distance, and tried to keep to the left hand side so as not to get sucked into a potential waterfall. I also didn't want to lose my bearings in the middle.

Every now and then the rapids would increase in size and I'd try to backtrack and find the easiest route. I ducked under one vine only to disturb a crocodile slithering off a rock.

Another time a huge snake swam right up to my canoe, reared up out of the water and I had to fend it off with my paddle. The canopy at this point was all-enveloping with hardly any visible sky, only the occasional beam of light piercing the foliage above.

At Stanley Falls close to Kisangani, Wagenia fisherman skilfully uses his scoop net

By far the most remote section of the Congo was the Luvua river, the outlet of Lake Mweru. Peppered with waterfalls and rapids, the entrance was guarded by abandoned T-62 tanks, littering the hillside by Pweto. This was the last town for 300 miles.

The day before I set off, I was approached by a leathery-faced South African bush pilot who, in his thick Afrikaans accent, told me: "Do you know there's still armed Mai Mai rebels in there man? I'm telling you if they catch you, they'll kill you, and it wont be a quick death." He continued: "A year ago two Belgian missionaries were captured, tortured, and had their testicles cut off and eaten. Their heads were then cut off and put on spikes outside their village."

I have to admit to briefly entertaining the idea of giving up, but quickly dismissed it and headed off before I changed my mind.

The Luvua landscape was unique. Golden coloured grass covered the surrounding hills, dotted with occasional abandoned huts built from volcanic-like rock. Large trees seemed to be covered by giant sheets of white silk blowing in the wind – in fact they were gargantuan house-sized spider webs. On one occasion while trying to sneak around a nasty rapid, I inadvertently brushed against one and was instantly covered in a million spiders – crawling in my mouth, my ears, up my nose. If I hadn't been such a rugged adventurer, I'd have screamed like a little girl; or at least, if a fisherman hadn't been sitting on a rock watching me.

Further downstream, soaring ochre coloured cliffs rose up thousands of feet from both sides, with stunted twisted trees clinging precariously to their sides. Everything was as dry as a bone; only by the river's edge was there greenery. The odd thunderous chasm from hell required a portage.

Congo river fisherman at Lukolela village, lower Congo

The Lualaba forms the middle and lower Congo River, and though I often experienced tremendous hospitality from the indigenous poverty stricken fishermen, unsavoury characters also became more commonplace. Trying to sneak past the town of Kabalo in the early morning mist, I was forced ashore at gunpoint by a couple of armed soldiers in a dugout canoe. I was greeted on the bank by what I can only describe as a mob of corrupt officials, and subjected to a rather aggressive search, taken away for questioning, arrested, and put into a jail full of prostitutes. My crime was for physically preventing the immigration official from leaving his office, as he had put my passport in his pocket and told me I wouldn't get it back unless I gave him $100. I eventually managed to resolve the situation. The next night, by way of contrast, I spent with a couple of delightful old fishermen on an island in the river.

The town of Kongolo was a perfect example of how former president Mobutu's criminal reign had caused the country's infrastructure to collapse. He squandered the country's wealth for his own personal gain, and the country's limited infrastructure collapsed. The shore was littered with the rusting, decaying hulks of giant river barges. A large tree growing out of one of the holds served as an example as to how long they had been there.

Further inland I discovered a roofless warehouse with three perfectly intact, albeit rusted, old-fashioned steam engines, abandoned to the elements.

In Heart of Darkness, Joseph Conrad described the lower Congo: "Like travelling back to the earliest beginnings of the world, when vegetation rioted on the earth and the big trees were kings. The air was warm, thick, heavy, sluggish. There was no joy in the brilliance of sunshine. On silvery banks hippos and alligators sunned themselves side by side. The broadening waters flow through a mob of wooded islands; you lost your way on the river as you would in a desert … this stillness of life did not in the least resemble a peace. It was the stillness of an implacable force brooding over an inscrutable intention. It looked at you with a vengeful aspect."

One stretch of the lower Congo River was known locally as "the abattoir", due to its past history of cannibalism and its current reputation for criminal activity. Because of this, I decided to hire four brothers as bodyguards. I met them whilst sheltering from a rainstorm in their tiny village miles from anywhere, and straight away I knew I could trust them. Armed with a shotgun and with my canoe lashed to their giant dugout, we paddled and floated for five days and nights on the river. Common questions from locals included: "Why haven't you cut his throat yet?" and "If you don't want to do it, tell us where your camping and we'll come and do it for you … We'll share his money."

Without a doubt, meeting the brothers – Valatay, Leonardo, Maurice and John – was one of the highlights of my trip. As desperately poor as they were, they were shining examples of how to retain your dignity and honour in the face of adversity. If my scrapes with the criminal element ever caused my faith in humanity to waver … these guys definitely restored it.

I left the brothers in Mbandaka, and three stone lighter after a life-changing five months, I eventually arrived at the Atlantic Ocean. My last night on the river was spent with delightful people in a desperately poor village in the coastal mangrove swamps. As a token thank you to the fishermen of the Congo, I gave my canoe as a gift to the village chief. He was chuffed to bits … as was I to have finally achieved my goal.