Sound travels much faster in water than in air, which is why whale calls carry so far.

The longer version

Water resists compression far more than air does, so a disturbance crosses it quickly and sheds energy slowly. Speed rises with temperature, salinity and pressure, and layered circulation bends travelling waves instead of letting them escape upward.

A deep channel where sound travels slowest traps calls and turns them back inward, allowing low notes to cross entire basins. This suits animals separated by darkness and distance, for whom a long call may be the only practical way to locate one another. Small air bubbles in the path, however, scatter the signal and shorten its reach.

Where this entry sits

Oceans and Sea Life looks at the salt water that covers most of the planet, from crashing waves and tides to the darkest deep-sea trenches. Expect notes on coral, fish, whales, sharks, jellyfish, shells, and the strange creatures that live far below the surface. The full list sits on the Oceans and Sea Life page, where every entry is listed in order.

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More From Oceans and Sea Life

Eight more entries

Tsunamis are caused by sudden shifts in the seafloor, often after a strong underwater earthquake.

Gulf Stream currents carry warm water across the Atlantic and moderate the climate of nearby coasts.

Underwater currents circle the globe, moving heat from the equator toward the poles.

Sailors once measured depth by lowering a weighted rope, a practice known as sounding the sea.

Shipwrecks on the seabed slowly become artificial reefs covered in coral, sponges, and barnacles.

Barnacles glue themselves headfirst to rocks, ships, and whales, and feed by filtering passing water.

The Dead Sea is so salty that swimmers float easily on its surface.

Salt water freezes at a lower temperature than fresh water, so polar seas stay liquid longer.

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