When a woman was pulled from the chilly Inner Harbor earlier this week, some may have been surprised to hear a day later she was conscious and expected to live.

She spent 30 minutes inside a car submerged in 53-degree water before being rescued by the Baltimore City Fire Department. But she’s not the only one to survive such an ordeal.

Last year, first responders were able to revive a woman who also was pulled from the harbor in even colder temperatures.

The fire department hasn’t released statistics, and a spokesman didn’t respond to a request for information. But dozens of people have been pulled from the harbor in the past decade, according to media reports.

While it’s unknown how many survived, medical experts say it’s the cold water itself that can give people a chance.

“Hypothermia is very dangerous and can cause death by cardiac arrhythmia,” said Dr. Jonathan Thierman, an emergency room physician at LifeBridge Health.

But in a strange way, he added, it’s also protective.

“Before it kills you, it protects your body by slowing down your body’s metabolism.”

That means your body needs to circulate less blood and oxygen for that half-hour under water, or in some documented cases, hours, Thierman said.

After a previous cold-water rescue in January of last year, Dr. Samuel Tisherman, director of the surgical intensive care unit at the University of Maryland Medical Center, called it basic physiology.

“Slowing things down buys us time to save somebody,” he said.

He was even researching surgical uses of hypothermia at the center’s Shock Trauma Center, which treats the region’s most severe trauma cases, including falls, car crashes and gunshot wounds.

A spokesperson said Thursday that it’s actually not that common for the center to admit patients after “submersion in natural water.” In the last five years, they found two such cases of hypothermia, including the recent rescue from the harbor. Five others occurred in summer months.

The U.S. Coast Guard, which saves thousands of people a year, set the ideal temperature around 60 degrees. Too warm and there’s no protection, it said. Too cold and survival becomes less assured.

There are a lot of variables, according to medical experts. The shock of the water can cause people’s hearts to just stop or impede their ability to breathe, leading them to take water into their lungs. The labor of swimming can also lead to cardiac arrest.

If hypothermia persists, a person’s respiratory, nervous and organ systems can start to shut down.

And lack of oxygen to the heart, lungs and brains can mean longer-term damage even if people survive.

Thierman, who didn’t treat the victims in the harbor rescues, said it’s likely that first responders found faint signs of life, like a faint pulse, and rushed the victims to the closest trauma center. Harbor victims may be helped because two of the city’s four trauma hospitals are close to the piers.

Doctors typically would work to resuscitate the unconscious victims, according to Thierman. They could use heated intravenous fluids and a treatment known as extracorporeal membrane oxygenation, which works through a life-saving machine serving as an artificial heart and lungs to pump warm oxygenated blood around the body.

That’s when doctors would know if someone could survive.

“There’s a saying in trauma medicine that you’re not dead until you’re warm and dead,” he said.

Doctors caution that while the cold can be protective and, in some cases, maybe even beneficial, plunging in the chilly harbor in your car is never recommended.

One exception could be for the athletic and hardy who brace the cold during the Maryland State Police Polar Bear Plunge fundraiser in January.

The story has been updated to correct the number treated for hypothermia after submersion in the water.