1) The Cricket World Cup is held every four years and features teams from around the world competing for the prestigious title.

2) The Great Barrier Reef in Australia is the largest coral reef system in the world and is visible from space.

3) International relations encompass the study of relationships between nations, including diplomacy, treaties, and foreign policy. It examines the interactions and dynamics among different countries in the global arena.

4) The Nile River, spanning approximately 6,650 kilometers (4,130 miles), is the longest river in the world. It flows through eleven countries in northeastern Africa, supporting various civilizations throughout history and serving as a vital source of water and transportation.