■ BA VI, VIETNAM: After trekking up the mountain through the thick monsoon fog and investigating some secret colonial ruins, I was aching for a swim. But where was the waterfall?

I drove around for an hour and all I found was an angry forest patrol who fined me $3 for trespassing around a lake. As I drove away in disgust I saw a fairground ride in what appeared to be someone's backyard! A theme park on private property? I couldn't believe my eye!

I was in Vietnam's jungle after all. As I drove around the property however it turned out it to be huge! This was a legitimate theme park built around a waterfall. But there was a catch....