I was swimming against a strong current as fast as I could, because about 5m below me, in crystal clear waters was a big green turtle swimming in the same direction. After about half a minute, it got bored with the strange creature in the sky with yellow flippers - it surfaced for a quick refill of air, then it was gone in the direction of the coral reef, and I couldn't keep up any longer. It lasted a minute at most, but it was the best experience in Borneo so far.

I had hired a mask, snorkel and fins to join a group of divers off the coast of Mabul and Kapali Islands. These are close to the Sidapan archipelago, which is renowned as one of the world's top dive sites. The divers that I spoke to were quite disappointed though, but that's probably because they were hoping to see big creatures such as the manta ray, devil ray, the hammerhead and the great white shark. Personally, I was happy enough with sightings of blue-spotted stingray, common lionfish, crocodile fish, barracuda, colourful starfish and anemones, and a host of other multi-coloured fish that I can't name. And I'd better not forget the sea snake and the big bloated triggerfish that kept attacking my fins. The sign in the office had said not to worry, as there are no aggressive creatures here. I beg to differ!

I have ended up spending three nights here on a floating hotel called Dragons Inn, but I was really only passing through in order to avoid a night in the border town of Tawau. I had already spent too much time in Tarakan - the last stop in Indonesia before the four-hour boat crossing into Malaysia. There was a good mangrove forest, which is populated by monkeys and fish that walk on water. Sadly I didn't see any of the latter.

Once across the border I found smaller and more organised towns than in Indonesia, brand new air-conditioned buses and good roads. In Semporna, I also discovered where all the tourists are, and I'm the only one who can say any words in Malay. There are also many Filipino refugees living here - if you study the map, the archipelago continues north and soon becomes the Philippines, so there are close ties with the people of Sabah.

Sorry that my photos are running a bit thin, but the weather remains overcast, and I don't have an underwater camera. So you'll have to make do with an expired sea creature that was photographed at the bustling fish market.