NatureWhy Is the Ocean Blue? Water, Light and Color
The ocean is not blue only because it reflects the sky. Learn how water absorbs light and why sediment, algae and shallow sand change its color.
Strange Ocean Facts
Follow the water from its blue surface to the ecosystems of the deep sea. Read in order or choose the question that catches your attention. Each story includes its sources.
- Why Is the Ocean Blue? Water, Light and Color
- Why is the ocean salty if rivers carry fresh water?
- Why Is Deep Ocean Water Cold If Earth’s Interior Is Hot?
- How Does Life Thrive Around Deep-Sea Hydrothermal Vents?
- How Do Octopuses Change Color So Quickly?
Nature
NatureWhy is the ocean salty if rivers carry fresh water?
Trace ocean salt from weathered rocks to rivers and the seafloor. Understand why evaporation leaves salts behind and what 35 parts per thousand means.
NatureWhy Is Deep Ocean Water Cold If Earth’s Interior Is Hot?
Most deep ocean water is cold because solar heating is concentrated near the surface and cold, dense water sinks to replenish the depths. Geothermal heat does not warm the whole ocean like a kettle.
NatureHow Does Life Thrive Around Deep-Sea Hydrothermal Vents?
At deep-sea vents, microbes use chemical energy instead of sunlight. They support food webs around hot, mineral-rich fluids on the ocean floor.
NatureHow Do Octopuses Change Color So Quickly?
See how octopuses use nerve-controlled chromatophores, reflective skin cells, and changing skin texture to camouflage themselves in mere moments.
One question leads to another.
Take a five-story journey through a topic.
5 QUESTIONS · GUIDED READING
Strange Ocean Facts
Follow the water from its blue surface to the ecosystems of the deep sea.
Start exploring ↗5 QUESTIONS · GUIDED READINGSpace Mysteries
Explore unusual worlds, hidden oceans and the clues astronomers use to understand them.
Start exploring ↗5 QUESTIONS · GUIDED READINGEveryday Science
Discover the surprising physics and chemistry behind familiar things.
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