Mother nature does it again. I reach the end of my final day totally exhausted, my mind totally boggled.

First was Gumantong caves (I need to check that spelling).

This was something off the set of an Indiana Jones film. Imagine that you are standing in cave as big as a cathedral, in the dark. As you walked in you had to battle with the stench of the droppings from the thousands of little bats that line the roof. There are funny bits of rope used by the farmers of the space to get up to the high roof of the cave.

This is the birds' nest cave, and it is nothing short of magnificent both in geology and human ingenuity. Every August the bats are joined by hundreds of migratory birds who build their nests here. Those nests are prized by the Chinese for use in bird's nest soup, alleged to have remarkable healing properties. Our guide, for example, braved the extortionate cost of this soup after she'd had an emergency Caesarian. The best nests are the white ones, which go for hundreds or even thousands of pounds per kilo.

But I'm visiting in July, so the bats have complete control. The droppings are harvested occasionally for fertiliser, but currently they lie thick on the floor. We walk on a gantry around the side, but you know you won't touch the handrail. Cockroaches of every size scoot across the floor boards.

To say that the bat poo forms a carpet doesn't capture the magnitude of the situation. This stuff is the depth of a whole sofa. It is oddly dry in appearance. Then the guide does her party piece. She asks a visitor to spit on the light brown soil. He does so. For 12 inches in each direction mat brown muck turns to shiny bodies as a hundred cockroaches erupt to capture the moisture. Moments later they are gone, reburied in the dung.

I'm sweating from the heat, the smell, but primarily the fear of these foul bugs. The guide takes us to see the white cockroach: the queen. The whole wall gleams to the torchlight, glinting off the backs of the insects.

We walk out into the light. And I start to relax. Frankly, I've just been through adrenal stress I cannot capture in words.

Then back into the car to get to the river boat trip. I hide in my book to regain my calm.

Then on to the river boat trip from Sukau. I am told that this is the highlight for many visiting the Sabah region, and my mind is telling me I should be buzzing, but the cave experience has left me a bit fried.

So I had already skimmed down the river in the narrow, shallow motor boat (the width of me and the depth of my shoes) for a good 15 minutes before I really engaged. Every passenger had been thoroughly warned that although the river affords unparalleled access to the local wildlife in it's natural habitat, there's no guarantee that the said wildlife might be on the river banks.

So the herd of pigmy elephants came as a shock. They are pigmies in the sense of being small elephants, rather than small in any other way. The sheer volume of tall grasses this lot were piling through beggared belief.

It was about 4pm and the elephants had had enough of the heat of the day. So they joined us in the river. A couple of the young males started wrestling with each other in the mud and sorting each other with water. They ignored us, coming very close purely by accident; we were no challenge to them. A slight stumble and we would have joined then in the fetid water. But those tiny eyes would click around every so often to make sure we were not in range. Where the orang-utans seemed wise like a curmudgeon in the comer of a pub., the elephants seemed wise like an elbow-patched geography teacher.

After a good while, the motorspittered into life and we carries on downthe river. Long tailed macaques and pig tailed macaques hung out on the banks, and then some proboscis monkeys. I was starting to get blaze about all these delights.

Then three rhinoceros hornbills flew over to oohs and ahs. These are incredible birds: this of a big beaked bird like a toucan, then put a rhino's horn on top of the bill. Sounds a bit freaky, but its extremely graceful in flight.

Then put-put-put-put back to the jetty.