Lesotho is the only independent state in the world that lies entirely above 1,400 m (4,593 ft) in elevation.
In fact, 80% of the country lies above 1,800 m (5,906 ft). Its lowest point of 1,400 m (4,593 ft) is thus the highest (lowest point) in the world.
Thabana Ntlenyana is the highest point at 11,423 ft. (3,482 m).
As for geographic regions in Lesotho, the only real lowlands are in the southwest along the Caledon River. The balance of Lesotho is a series of foothills and plateaus fronting mountains, central, east and north.
Significant rivers include the Calendon, Makhaleng, Malibamatso, Matsoku and Orange (or Senqu).
The Orange River at about 1,300 miles (2,100 km) in length is one of the longest rivers in Africa. It rises in the Lesotho Highlands as the Sinqu River. In South Africa it flows west, passing the southern edge of the Kalahari Desert and winds through the Namib Desert before draining into the Atlantic Ocean.
Makhaleng River Gorge, Lesotho Arcimboldo at en.wikipedia