Hours after the waters of the Gulf of Mexico swept through her house, Donna Knight emerged in a windbreaker and boots to try to get her Chevy SUV to higher ground.

“It came through — the whole ocean,” she said, describing a night of howling wind, frightening bangs and flying debris as Hurricane Idalia blew through Cedar Key, a conglomeration of tiny islands connected by bridges that juts three miles into the Gulf.

By noon on Wednesday, the center of the Category 3 storm had passed, and she and her 19-year-old son knew they had survived. “We should have gotten off the island,” she said.

The homes in her neighborhood, many of them Old Florida-style beach houses, were battered and flooded, though some of their metal and wooden shutters remained on windows. The storm surge lingered on some roads, smelling of salt water and gasoline.

Tree branches littered the street. A chair was tossed upside down in front of Ms. Knight’s door, and her boat had been carried east up the road, she said.

An RV resort near the entrance to Cedar Key was submerged by several feet of surge. A newly renovated hotel with a tiki bar, its doors painted in cheerful colors, was also invaded by water.

Officials had estimated before Idalia made landfall that perhaps 100 people were riding out the storm on Cedar Key. It was unclear how many had left the island immediately afterward.

By early afternoon, Chief Edwin Jenkins of the Cedar Key Police was turning people away from town, which — at least before Idalia — consisted of a modest main street, two museums and the smallest public school in the state.

“The island is closed,” the chief said.

Crews of volunteers with airboats assembled near the bridge to town on State Road 24. They put on life jackets and prepared to make water rescues.

Ms. Knight, 62, a 20-year Cedar Key resident, had every intention of heeding the mandatory evacuation order ahead of Idalia, she said. “My bags were packed.” She just needed gas and groceries, and would join her husband and mother-in-law near Orlando.

But her son didn’t want to go. “I wasn’t going to leave him by himself,” she said.

So she stayed and listened to the roar of the hurricane as the waters rose — across her backyard, into the first floor, across the street. “My backyard, you can’t even see it,” she said. A tree blocked her into the house, but she eventually managed to climb out.

The water appeared to be waist high inside her house, she said, but higher outside.

Her water taps went out at about 8:30 p.m. on Tuesday night, she said. The power held on until about 3 a.m. Wednesday.

Ms. Knight and her family are clammers, one of seven such businesses in Cedar Key, she said. A sign at the entrance to town proudly lets visitors know that this is a shellfish town.

Ms. Knight said she worried that the business would not survive. “It’s going to be a setback,” she said.

Her son, who has diabetes, had an insulin stash, while she had lunch meat and food she had made in a crockpot on Tuesday night, Ms. Knight said. They had enough water in jugs “at least for today,” she said.

By Wednesday afternoon, the tide, part of daily life for islanders, was rising. Small waves lapped onto the road, threatening to swamp it again. The car had a new engine. Maybe she could save it.

“It’s OK,” she said. “We’re alive. For now.”