The ocean can look completely calm from the surface while enormous waves move through the water below.

These hidden waves can stretch for miles and carry vast amounts of energy through the deep ocean.

Known as internal waves, they form within the ocean rather than on its surface, often along boundaries between layers of water with different densities.

The Giant Waves Hidden Inside the Ocean explores the strange physics of these underwater giants and their surprising role in Earth's oceans.

Unlike ordinary waves, internal waves can travel along the boundary between warmer, less-dense water and colder, denser water below.

Some can reach hundreds of meters in vertical height.

From above, the surface may show almost no obvious sign that anything enormous is moving beneath it.

Internal waves are particularly i ...