Top 3’s Top 3 Tallest Mountains in the World 1. Mount Everest-29,029 feet 2. K2-28,251 feet 3. Kangchenjunga-28,169 feet Top 3 Longest Rivers in the World 1. The Nile-6,650 2. The Amazon-6,400km 3.The Yangtze River-6,380 km