Australia is a dangerous place. I had no idea quite how dangerous, but now we're in Queensland, we seem to have become more aware of this. Hard not to really, when we're surrounded by signs warning us about possible hazards at every turn.

According to Bill Bryson's Down Under (which we've both become slightly obsessed by), “Australia has more things that will kill you than anywhere else. Of the world's ten most poisonous snakes, all are Australian. Five of its creatures – the funnel-web spider, box jellyfish, blue-ringed octopus, paralysis tick and stonefish – are the most lethal of their type in the world.”

Now, I felt I was at least partly prepared for some of these dangers – namely, snakes. However, had I known that 'only' 14 species of snake are seriously lethal in this part of the world, then I might have seriously rethought this part of the trip. Among these species, the most deadly is the taipan, which carries a venom 50 times more deadly than that of the cobra. James had to take this picture at the Lone Pine Koala Sanctuary, as I couldn't even bring myself to look at it.

On arriving in Sydney, we learned all about how deadly the spiders are here – Kate nearly walked into this golden orb spider in the middle of the Botanical Gardens, and Tim whispered to us that he regularly has to remove redbacks from their washing basket in their flat. The funnel-web spider is a big problem in the capital: the most poisonous insect on earth (are you seeing a pattern here?!) it has a fast-acting venom which produces seizures, blueness of the face, and then death.

In the last two weeks, we've had cause to add all manner of new dangers to this list. We've been warned off swimming in the sea north of Mackay (about halfway up the coast) because of the presence of jellyfish, even in winter. And not just any jellyfish, but box jellyfish, the most poisonous creature on earth.

And then there are the crocodiles. Apparently estuaries are the most dangerous place in the country because of the numbers of crocs who swim up them in search of a meal. The campsite we stayed at in Rockhampton by the Fitzroy River had a huge sign warning us to stay within the designated camping area because crocodiles had been known to frequent the river banks. I didn't see any electric fences, so I don't know how they could be so confident that crocs would stay out of 'designated camping areas.' As a precaution, once we were in our camper for the night, I refused to leave again until morning.

Now we're in far north Queensland, there's a whole new creature to worry about – the cassowary, which looks like a cross between a peacock, an emu, and a veloceraptor. The cassowary has razor claws so sharp that it can slit a human being open from neck to belly in seconds. The warning signs advise you to 'keep calm, never approach a cassowary, and if it looks like it's going to attack, get behind a tree.' Sorry, but if I meet one of these things I am sure I will be running for the hills.

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.