Rip currents and undertow are two entirely different water transport features
Dear Tom,
I read the article about rip currents in the Sunday Chicago Tribune. Is this the same as
what we used to call "undertow" when I was a kid?
Judith Allen, Chicago
Dear Judith,
Rip currents and undertow are two entirely different water transport features that occur
in the shore area of oceans and large lakes like Lake Michigan. Both move water
brought to the shore by waves back into the lake (or ocean).
A rip current, flowing at speeds up to 4 m.p.h., is a surface flow of water, usually 20 to
100 feet in width, flowing outward from the shore. It won't pull a swimmer beneath the
waves, but it can carry him a few hundred feet out. It's literally a "river in the lake."
Unlike the powerful, localized and dangerous surface rip current, undertow is a brisk
bottom flow in shallow water (2-4 feet deep). It transports water carried onto the beach
by breaking waves, and is a lesser threat.