"It's hard to figure it out where you are going to start over", said one resident. Its top sustained winds are now 110 mph (177 kph) and the center of the storm is about 15 miles (25 kilometers) inland from Fort Myers.
It's still raking Florida with devastating storm surges, winds and rain.
Hurricane Harvey unleashed extensive damage in southern Texas and parts of Louisiana as it brought excessive rainfall and catastrophic flooding, killing at least 74 people. Last week it killed at least 37 people as it crossed the Caribbean.
As crews laboured to fix the lone highway connecting the Keys, residents of some of the islands closest to Florida's mainland were allowed to return and get their first look at the devastation two days after Irma roared in with 130mph winds.
FPL, the state's biggest power company, said about 1.9 million had no power on Wednesday, down from more than 3.6 million on Monday.
The city of Jacksonville in northeast Florida ordered urgent evacuations on Monday.
"Extremely high tides combined with heavy rain has resulted in widespread, unsafe flooding throughout Downtown Charleston", said a bulletin from the weather service office in Charleston.
More than 180,000 people huddled in shelters in the Sunshine State.
Florida Gov. Rick Scott said Irma's wrath is unprecedented, warning that storm surges could be deadly.
"What we feared the most was the surge", he said on MSNBC.
"We are finding some remains", she said in an interview with CNN. "The low is likely to dissipate by Tuesday evening".
- The scale of damage to the Florida Keys will become clearer by Tuesday 7am, when residents will be allowed back in. Drivers must provide proof of residency or business ownership.
Search and rescue operations continued in the Keys and Southwest Florida.
The Department of Defense warned that the 10,000 people who stayed in the Keys may be forced to evacuate.
What was the total damage from Irma?
Food, water and gas deliveries were starting to return in Central and South Florida as the demand swells from returning evacuees.
Almost 4.5 million homes and businesses statewide lost power, and utility officials said it will take weeks to restore electricity to everyone.
Scott said 65% of Florida was without power.
He described whiteout conditions, with howling winds that sucked dry the gulf side of the narrow island, where the tide is usually 8 feet deep.
"I said, "Let's go and live the good life in paradise", she said.
"We'll get some water to them as far as the drinking water", Gastesi told the station, adding that he's confident authorities will be able to help the community recover and rebuild. Mobile home residents and Florida evacuees camping in RVs were urged to head to one of seven storm shelters in the area.
Two people died in the storm on Monday, state officials said: Zhen Tain, 21, of Florida, who died in a two-car wreck on Interstate 77 in Columbia, and Charles Saxon, 57, of Calhoun Falls, who died when a limb fell on him.