TAMPA, Fla. (AP) — Water driven back by powerful winds drained from Tampa Bay as Hurricane Ian approached Florida’s Gulf Coast on Wednesday, and some dared to venture out on the exposed bay floor.

Ian eventually made landfall as a major hurricane near Fort Myers, about 100 miles (160 kilometers) to the south.

A number of people posted photos on social media of themselves and others walking out on the exposed sand and silt, despite warnings from local officials to stay back. Tampa Bay has a normal average depth of about 12 feet (4 meters).

The phenomenon of the bay emptying out also occurred in 2017 when Hurricane Irma caused another so-called negative surge, according to experts.

Because hurricane winds blow counterclockwise, the winds at the northern edge of Ian’s circular system were blowing from east to west with such force that they pushed bay water into the Gulf of Mexico.

More about Hurricane Ian

Water eventually refilled the bay.