On the way back from Niah Caves, we stopped to visit an Iban longhouse. The Iban are the largest of the native tribes of Malaysian Borneo, and longhouses are their traditional dwellings. As the name suggests, longhouses are big long houses within which all members of an individual tribe can live together. They come in all shapes and sizes - some more traditional and wooden, others new and made of brick and concrete; some with satellite dishes and new cars parked out front, others built by poorer tribes from a patchwork of rusted corrugated steel and salvaged wood.

We entered the longhouse from one end into a large corridor that stretched the entire length of the longhouse. This was the main shared space of the longhouse, the centre of communal life for the tribe. The corridor was about 5 metres wide and 200m long, with a floor of polished timber. All the way down the left hand side were the front doors to the apartments of individual families – about 80 in total. The beauty of a longhouse is that as the tribe grows and more families join the tribe they simply build more apartments on to the end of the house.

As walked down the corridor a couple of small children peered around one of the doorways, giggling with amazement at the foreigners and shoving their terrified younger sibling out in front of us, who shot back inside like a startled cat. We snuck a look in the open door after him and caught a glimpse of large sofas, rugs and a widescreen TV. A comfy modern home.

On the right hand side of the communal space, doors open out at regular intervals onto an exposed wooden balcony, where rice and wood and washed clothes are dried and feats are held during important festivals (including the annual harvest festival). Sitting on the floor in the breeze of these doorways were many groups of older tribespeople, whiling away the day with gossip.

Halfway down the longhouse is the chief's apartment, outside of which, hanging from the ceiling in the centre of the corridor is a collection of wicker and rope netting. As we got closer, we saw the skulls hanging within. These were the skulls of the tribe's defeated enemies – the Iban used to be head-hunters. Inquiring of a group of old men and women quietly chatting near the skulls, our guide told us that they belonged to fellow Iban from a rival tribe that they fought long-ago.

Talking further with the tribespeople in Malay our guide told us that they were quiet today because they were all tired from staying up late to watch the football, and most of the younger men weren't even awake yet, having drunk a little too much rice-wine with the game. Once they ascertained that we were from England, one of the men slapped his hand to his head and said, 'England? Wayne Rooney! England he play badly! No good! Play better Man United!'

From Brunei we took a short 6 hour bus ride back into Malaysian Borneo, crossing the border at Kuala Belait. I then spent 16 hours holed up in a hostel in Miri with the tail-end of a bout of food-poisoning, willing myself well in time for a tour to the Niah Caves that we had booked for the following morning. Sarah tells me she spent a lovely afternoon exploring the 'sights' (browsing the shops and getting a pedicure).

Aside from a mild fever virtually indistinguishable from my base-level of tropical sweatiness, the next morning I was good to go and we set off with our guide Ken west on the coastal road to the limestone cliffs of Niah.

The Niah Caves are the result of similar limestone rock formations to those we saw in Halong Bay in Vietnam – they're enormous humps of rock, big sore thumbs in an otherwise flat jungle landscape. In Halong Bay water still laps the base of these rocks, in Niah the sea has rolled back several miles leaving jungle and more palm oil plantations between the beach and the caves.

Niah and its big brother Mulu (another set of caves in Sarawak) housed some of the oldest recorded human settlements in the region. Inside the mouth of the Great Cave at Niah, 'modern' human skulls have been found in a highly organised burial ground that dates back 40,000 years – the oldest in the whole of S.E.Asia – as well as a series of very faded cave paintings of boats and monsters dated at 20,000 years old.

We strolled the 4km from the camp to the caves, protected from the rainforest by a raised wooden walkway, before climbing the wooden staircase up the face of the limestone cliff to the enormous cave entrance. Once inside the mouth of the Great Cave, sunlight quickly became a distant memory and our torch did little to penetrate the heavy darkness around us. Following our guide's heels, we felt our way over damp wooden walkways deeper into the cave system. Only the clicks and screeches of bats and the echoes of dripping water gave us an idea of the scale of the space, until we rounded a corner and saw light lancing down from holes in the cave roof 50 metres above us.

Tourism in the Niah caves exists side by side with two older industries – guano (bat shit) farming and birds' nest collecting. Nitrate-rich guano from the 2-3 million bats living in the caves is shovelled up daily by groups of locals living in camps within the caves and sold as an expensive natural fertiliser. The ammonial stench hit us like waves in the more popular bat-caves. I've no idea how the farmers live with it day-in day-out.

Bird's nest collecting is a less disgusting but much higher-risk profession. Collectors ascend 100 foot high bamboo poles to knock down Swiftlet nests attached to the cave roof. The saliva that the birds use to construct their nests has supposed aphrodesiac properties that make them the most valuable ingredient in Chinese 'bird's nest soup'. It is this rich export market that causes otherwise sane locals to climb to such heights with no ropes.

Both these professions require their practioners to live in the caves in semi-permanent camps to guard their territories from interlopers. As we walked through the caves, we came across a guano farmer standing by the walkway on a rock in the milky half-light, smoking a cigarette and looking very much like an overgrown Golem – wearing only shorts and a non-functional head-lamp, he was skinny and pale with clammy-looking skin that stretched over a little pot belly. After our guide exchanged a few words with him ('Nice weather'?!?) we walked quickly on.

We flew into Brunei almost on a whim, as it was en-route between the Sabah and Sarawak provinces of Malaysian Borneo. We're glad we did, although I very much doubt we'll be going back. Brunei is deeply weird, and very boring unless you happen to be a Sultan.

Bandar Seri Begawan is in the midst of a city-wide ego-trip. The 15th of July is the Sultan's 64th birthday, and to celebrate the entire capital city has been bedecked in flags, ribbons and 20 foot high posters of His Majesty in various action man-type uniforms. This in a town that already has a dedicated 'Royal Regalia Museum' proudly displaying the thousands of gifts that other nations have presented the Sultan arranged around a pimping solid gold chariot.

(Top 3 Worst Gifts in the Regalia Museum:

3. 2ft tall, solid crystal statue of a rearing wild horse from Indonesia. Classy.
2. A cartoon, smiling, marble walrus from Canada. Nice work.
1. A wooden shield-shaped presentation plaque (kind of like my grandpa's bowling prizes) surrounding a moody and slightly out-of-focus photo of the Syrian president. 'I thought to myself, “What would make the perfect gift for a Sultan?” and then it struck me: A photo of yours truly')

Outside the capital we also visited the Sultan's Polo Club (he keeps Argentinian horses in air-conditioned stables), and the $1.1BN Empire Hotel (golf course designed by Jack Niklaus, penthouse $130K a night). The Sultan's younger brother is still lying in low in London having been discovered to have gone on a $16BN spending spree whilst holding the post of 'Finance Minister' in the late 90s. It's pretty sickening how much wealth is held in the hands of so few, and just how extravagantly it is being spent infront of the people who should be sharing it. You would have thought the country ripe for revolution, but the thought honestly doesn't seem to have occurred to them. They're probably all just too bored.

We were only there for a day and a half, but were already struggling with the boredom so decided to visit the premier (only?) amusement in Brunei – Jerudong Amusement Park. When it was opened by the Sultan in 1997 all the rides were free. Now half the rides are broken, and when we turned up the rest were shut for prayer time. Even the rebellious teenage skateboarders had sat down and faced west. Too late to get our money-back, we wandered around the ghostly quiet park till the rides opened again and we could get onto the go-karts.

My favourite ride at Barry Island Fun Fair has always been The Jungle Ride. You sit in a plastic boat in a couple of inches of murky water and wobble through a cardboard wilderness as a series of plastic animals take it in turn to pop out from behind trees and bushes. It's awesome.

Travelling up the Kinabatangan River in Borneo is kind of like The Jungle Ride. The water is just as murky but the boat is a little faster, the wilderness a little wilder and the animals a little furrier. Our stay on the river definitely ranks up there as one of my highlights of our trip thus far.

From base camp near Sepilok, we drove for a couple of hours over gravel roads to a small village on a river where we loaded our packs and supplies onto speed-boats that took us upriver and into the wilderness. On the way up the river we spotted our first wild orangutan, sitting in between two branches of a fig tree about 15 metres up over the water. As we slowed down to stop at the bank beneath him he took a look down at us, then resumed his lunch - slowly chewing his way through branch after branch of the tree's fruit.

'The Man of the Forest' is a solitary, territorial animal, and so spends most of his life on his own. Each time we saw orangutans over the next few days, slowly moving through the trees or sitting watch over the river with their soulful dark eyes, it was hard not to feel that they might be lonely, especially in contrast to the happy, playful packs of macaques roaming the treetops.

Over the next few says we set out on a number of dawn and dusk boat rides up and down-river, one day trek into the jungle and finally one night trek. We saw the most wildlife out on the river (orangutans, long-tailed macaques, proboscis monkeys and gibbons, as well as plentiful hornbills and egrets and even one incredibly menacing estuarine crocodile) but the treks into the jungle were just as exciting.

The rainforest is unlike any other environment I've experienced. As you step out from the safety of camp you can feel some very basic survival instinct flip into high gear as your brain struggles to process the sheer density of new sights and sounds, sorting the dangerous from the mundane: screaming cicadas, whirring mosquitos, the crash of foliage as birds move ahead and all around you the shifting green shadows of lianas, leaves and ferns. Through this aggressive terrain our guide strolled barefoot, only slipping on low rubber shoes at night in deference to the fire ants.

Sarah coped with the stresses of the jungle incredibly well during our stay, especially considering she doesn't like camping, has never been hiking before, and is morbidly afraid of half the things we were actively looking for. Creeping around in the jungle during our night trek with eyes wide and shoulders tensed, her head torch was like a strobe-light as she scanned the branches above her for opportunistic pythons and spiders, but by the time we got back to camp she had the biggest smile of all of us at the things we had seen. (Of course this made it all the more ironic given her subsequent delayed 'reaction' to the experience, but she'll fill you in on that in her next post)

Over the last several hundred years the rainforest has been eroded by various colonial endeavours – tobacco and rubber plantations, hardwood logging – and is now further threatened by the modern blight of palm oil plantations. Oil from the palm's fruit can be used to make cooking oils, soaps, and even bio-fuels, and these plantations now cover the majority of all land in Borneo. Ironically, this actually makes it easier for us to see some wild animals as they are concentrated in a smaller area. Other animals that need more space like elephants fare less well, and the government is struggling to balance the needs of their developing nation (and the benefits of a renewable energy source) with the protection of these endangered species. As we drove home in our minibus, stinking and filthy from the jungle, through the window we saw islands of rainforest in a sea of palm plants, and wondered which way the tide will turn.