A U.S. Marine startled Vicksburg officials when he went for a winter swim in the Mississippi River.

Staff Sgt. Ryan Hoover, 25, was in his native Vicksburg on leave when he donned a wetsuit Monday and went swimming with the air temperature below freezing outside.

Several people alerted authorities. It’s much more common to see barges in the swift moving river than a person, especially this time of year.

Coast Guard officials say Hoover was picked up by a private boat when its crew told him authorities were concerned and “suggested” he abandon his swim or law enforcement would come get him. He seemed unfazed by the chilly temperatures of strong currents.

Hoover says he was preparing for a future attempt to swim across the river. He said he carried a backpack of food that “would help keep me alive if the current carried me to hell or something.”

He said he had planned to swim several miles down the river then jog roughly six miles to his family’s home.

“I’ve been swimming in this river since I was a kid,” he said. “I do want to apologize to all of the law enforcement officials who had their day disturbed because of me. I really didn’t mean to cause this ruckus.”

Hoover was questioned by a Warren County sheriff’s deputy and two Vicksburg police officers. He was released after Coast Guard officials made clear that the swim was legal, said Sheriff Martin Pace.

Federal and local officials said swimming in the Mississippi River is legal, though dangerous.