BE careful. Don’t be taken in by the calm current of the wide River Digul. When it is high tide at full moon, a wave, usually called the current head, may appear from the river estuary. It roars like the sound of the engines of a Hercules aircraft and may rise as high as 4 meters.

To vessels and rafts that transport people, basic necessities or timber that happen to sail by, this particular wave may turn into an imminent danger—and it has