Rip current

A narrow, fast-moving current that flows away from shore through the surf zone. It returns water brought toward the beach by breaking waves.

Wave setup: The rise in mean water level near shore caused by waves breaking and transferring momentum. Breaking waves pile water against the beach, creating pressure that drives offshore flow.
Rip current safety: Practices for reducing the risk of injury or drowning around rip currents. Safety guidance focuses on recognizing hazards and avoiding counterproductive responses.
Channel rip: A rip current concentrated in a channel, often between sandbars or beside a structure. A seabed channel can confine the offshore flow into a narrow, persistent stream.
Undertow: A popular term for water moving seaward beneath incoming waves, often used imprecisely for rip currents. Unlike the imagined subsurface pull, a rip current is a visible or surface-reaching offshore flow.
Surf zone: The nearshore region where incoming waves break and their energy dissipates. Rip currents form within this zone and carry water back through it.
Rip current detection: Methods for identifying rip currents from shore, aircraft, or instruments. Detection helps beachgoers and lifeguards locate hazardous offshore flows.
Flash rip: A short-lived rip current that forms suddenly as wave conditions change. Rapid changes in wave breaking can create a rip with little warning.
Rip tide: A colloquial name often applied to rip currents, though it incorrectly suggests a tidal cause. The name obscures the wave-driven mechanism and is not the preferred technical term.
Longshore current: A current that flows parallel to shore, driven mainly by waves approaching at an angle. Its water can converge and escape offshore through a rip channel.
Lifeguard: A trained professional who monitors aquatic areas and rescues people in danger. Lifeguards watch for rip currents and assist swimmers caught in them.

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