Why do lagoons form behind reefs?
Show answer & explanation
Answer: Reef blocks wave energy
Rainwater collects there — Wrong. Lagoons aren't rainwater pools. They're seawater areas protected by coral reefs or barrier islands that block wave energy.
Reef blocks wave energy ✓ — Correct! Lagoons are shallow water bodies separated from the ocean by a barrier (reef, sandbar, or barrier island). The barrier blocks wave energy, creating calm water behind it. Sediment can't be carried away, shallow water warms, and unique ecosystems develop. Atolls have central lagoons!
Tides create pools — Wrong. Tides do affect lagoons, but lagoons form because barriers block wave energy, creating sheltered shallow water.