RÍO PARAGUAY The 1,550-mile (2,550-km) Río Paraguay, another legendary South American river and gateway to Brazil’s Pantanal and Mato Grosso ecosystems, makes for a fascinating alternative for those who want a little less jungle and a lot more open space.
HUANG HO For stunning mountain scenery and a chance to see ancient and modern civilizations side by side, head for China’s lifeline, the Huang Ho. The river runs east for 3,400 miles (5,500 km) from the Bayan Har Mountains in western China.
ALLAGASH RIVER This 95-mile (150-km) waterway in the northeast USA might be comparatively short, but it’s thrilling to explore. With its rapids, black water, and deceptively placid appearance, the Allagash commands respect at every bend.
NIGER RIVER Coursing for 2,600 miles (4,200 km) through the southern Sahara, the Niger River, with its combination of relentless heat, surprise sandstorms, and serpentine curves, will test even the most experienced navigator.