V. Why Do Some Animals Navigate So Perfectly?
Birds migrate thousands of kilometers.
Sea turtles return to the exact beach where they were born.
Salmon find the same rivers after years in the ocean.
Scientists know these animals use several navigation methods, but many details remain mysterious.
VI. The Deep Ocean
More than 70% of Earth’s surface is covered by oceans.
Yet much of the deep ocean remains unexplored.
Researchers continue discovering new species, unusual ecosystems, and strange geological formations that nobody knew existed.
