Rip currents are powerful, narrow channels of water that flow away from the shore. Rip currents occur along the Atlantic, Pacific, Arctic, and Gulf of Mexico coasts of the United States, as well as along the shores of the Great Lakes. These currents (often incorrectly called rip tides) can flow up to 8 ft per second (2.4 m/s), which is faster than the average person can swim.
Rip currents are created due to set-up near the shoreline. Set-up is a slight increase in water levels compared to those found seaward of the surf zone. Set-up creates unstable conditions that are eventually relieved through the formation of rip currents. These dangerous currents generally form at a low point in a sandbar. Swimmers should be especially cautious during storm events, which may increase the frequency and strength of rip currents.