Is the “undertow” on Lake Michigan the same as the “rip currents” that we are warned about today?

Dear Tom,
When I was growing up, we had “undertow” on Lake Michigan. Is that the same as the “rip currents” that we are warned about today?
— Dennis Cusumano, Winthrop Harbor
Dear Dennis,
While both pose hazards to swimmers, rip currents and undertow are two entirely different water-transport features that occur in shore areas of oceans and large lakes. Both move water, brought to the shore by waves, back into the lake or ocean. The far more dangerous rip current, flowing at speeds up to 4 mph, is a surface flow of water, usually 20 to 100 feet wide, flowing away from the shore. While it won’t pull a swimmer beneath the waves, it can carry one a few hundred feet out. It’s literally a “river in the lake or ocean.” An undertow is a brisk bottom flow in shallow water (2 to 4 feet deep) that transports water carried onto the beach by breaking waves, and is a far lesser threat.