On this laid-back boat, there are only six of us and – as Nam tells us soon after boarding – we are not beholden to any schedule. That leaves us with less than stressful dilemmas like choosing between a languid paddle through the karsts or lying back with a book on the boat’s sundeck. Below deck, the wood-panelled quarters are tasteful, if not opulent, and large portholes offer a view of the scenery in air-conditioned comfort.

On our first day, we get an afternoon master class on the art of making goi cuon (Vietnamese fresh spring rolls) from Mr Vuong, our talented chef. Although I once lived in the country and have returned on numerous occasions, my mastery of the subtle art of Vietnamese cuisine has so far proved elusive, and my clumsy attempts at this classic are no match for Vuong’s perfectly executed versions. Later I find a much less taxing – and far more enjoyable – diversion by leaping from the sundeck into the warm ocean for a splash around.

The following morning, I pilot my kayak through a narrow passage that spears through the heart of one of the outcrops. I’ve been paddling for a good 10 minutes in the pitch-black tunnel, using my oar to fend off stalagmites and stalactites. Suddenly, shards of sunlight penetrate the darkness and seconds later I am drifting out into a giant lagoon hemmed in by steep cliffs.

Besides my fellow intrepid explorers from the Dragon Bay junk there’s not another soul in sight – no party boats, no processions of tourists trekking into caves, no floating hawkers selling tourist tat. As eagles soar high above and animal noises emerge from the jungle, it is impossible not to be thrilled by a destination that, thus far, still offers the chance to be alone.

Bai Yu Long Bay hit list