Hurricane Erin has intensified to a Category 4 storm affecting the Caribbean, impacting flights and cruise itineraries, with warnings issued for the Bahamas and Turks and Caicos, and it poses a significant coastal threat to the U.

Despite changes in intensity, Erin’s size will drive dangerous surf and massive seas along much of the United States East Coast, as well as Atlantic Canada and Bermuda waters.

Hurricane Erin was taking aim at the U.S. East Coast on Tuesday evening, according to forecasters who are warning Americans of life-threatening rip currents along beaches that could persist for days.