At the back of the boat are a dozen fresh sides of beef and right under my garden hammock, stood on end, are two big double mattresses still in plastic wrap. Upstairs, another 40 or so hammocks compete for every tiny available scrap of space. Shortly after 9 p.m. we're off, headed up the river toward the village of Novo Airao, an eight-hour trip. In a few minutes the lights on the boat go off, the talking slowly dies away and we settle in for the ride, a cool humid breeze flowing past, the droning hum of the engine and its gentle vibration carrying everyone off to sleep.