Teresa Jones, 63, an artist, described the shock she had felt as she had looked over Charleston Harbor and watched the ocean encircle her home and much of the city’s lower peninsula, an area that remained largely flooded into Tuesday. Ms. Jones’s home escaped major flooding by a few inches. “I didn’t think it was going to be this bad,” she said. “I’ve never seen the water so high.”

South of downtown near Folly Beach, Walter McAdory, 68, a retired Naval planner and clam farmer, burned a pile of debris and surveyed a destroyed dock and fishing shack he built after Hurricane Hugo, in 1989. As the worst of Irma struck, the several miles of tidal marsh between his home and nearby Morris Island were submerged beneath the biggest waves Mr. McAdory had ever seen there. “I was very surprised,” he said. “This was definitely the worst since Hugo.”

France’s president visits storm-hit islands in the Caribbean

St. Martin and St. Barthélemy, known for idyllic beaches that have long been a draw for tourists, were left devastated after Irma tore across the islands. Roofs were torn from homes, and power and water were knocked out on both islands. At least a dozen were killed as a result of the storm, according to The Associated Press.

During a news briefing at the airport in Pointe-à-Pitre, Guadeloupe, President Macron promised government support to rebuild the devastated islands, which he planned to visit later in the day.

“I am here with three government ministers to express firstly the solidarity of the international community following what happened after Hurricane Irma and to say that all of France stands side by side with those who lost everything, some even lost their loved ones,” Mr. Macron said. French relief operations are being coordinated from Pointe-à-Pitre, which was spared the widespread destruction seen on other Caribbean islands.