For those who drown in the Schuylkill River, the trouble usually comes suddenly.
One moment they're with friends and family cooling their feet in water about a foot deep.
A second later they've stepped off an underwater ledge they never saw and are caught in a strong current, Reading Fire Marshal Jeremy Searfoss said.
Even good swimmers can be overwhelmed, and the situation is even more dire for inexperienced swimmers, he said.
There are no lifeguards to help them, and very few swimmers wear personal flotation devices, he said.
“All of a sudden they're getting swept downriver and unable to keep their head above water,” he said.
By the time rescue workers are called and reach the scene it can be too late to save them, he said.

The presumed drowning of a 19-year-old Reading man on June 29 along a popular stretch of the river near the city's Riverfront Park has drawn new warnings from officials about swimming in the Schuylkill, which while legal is also dangerous.
No city ordinance prohibits swimming in rivers, and it is clear why dozens are drawn to the Schuylkill when it's hot out, especially with Reading only having one public pool, officials said.
But Helinson Hernandez's death shows that river swimming is not worth the risk, Searfoss said.
“The river is deceptively inviting,” he said, “but we highly discourage (entering) it.”
Hernandez died in the area along Riverfront Drive commonly called “Penske Beach,” though it has no connection to the Penske corporation other than proximity to a nearby Penske property.
Drowning statistics for the river were unavailable, but officials agreed that numerous people have died in that section of the Schuylkill over the years.
Crews were called June 29 after bystanders said a male had gone into the water and never came back.
Hernandez's body was recovered by rescue personnel who braved early evening thunderstorms to search for him.
An inflatable boat was deployed to conduct a surface search while dive teams from throughout the area were assembled. One of those teams found the body.
He was pronounced dead that night.
Preliminary results from Monday's autopsy on Hernandez were consistent with his death being an accidental drowning, but a final ruling won't be made until toxicology tests are complete, the Berks County coroner's office said.
City administrators on Wednesday released a statement that they were saddened by the drowning and stressed that accidents can occur when swimming in natural waterways.
“Rivers can be fraught with hazards such as currents, underwater vines and branches, and submerged rocks which increase the possibility that a swimmer could face danger,” it said.
Riverfront Park, which is owned by the Reading Redevelopment Authority, is an attractive location for residents and visitors alike but has had problems, officials said.
“While we strive to schedule special events at the park, we are unable to do so every weekend,” they said. “Unfortunately, some visitors do not treat the park with the respect it deserves, resulting in issues such as excessive drinking, noise and littering. The Reading Police Department and public works (department) are doing their utmost to address these concerns.”

As a safer alternative to swimming in the river, officials encouraged people to use facilities such as Schlegel Park pool, which is open to the public, as are the splash pads at playgrounds around the city and Reading's Wacky Water Wednesday events.
Residents may also consider other pool facilities such as the Clinton Street Pool operated by the Olivet Boys and Girls Club, College Manor Pool, which requires membership, and indoor pools at Reading Senior High School and Northwest Elementary School, officials said.
“Safety is our top priority, and we urge everyone to remain vigilant and choose designated areas for water activities,” officials said.
City Council President Donna Reed said residents have swam in the river for many years, especially young people, and that a kayak and canoe ramp in the Riverfront Park section makes access easier.
But drownings there also go way back, she said.
“It's just horrible,” she said of those tragedies.
Council will hold a committee of the whole meeting Monday in which Riverfront Park is expected to be among the topics discussed, she said.
Know your limits
Deputy Coroner George Holmes said even rescue workers with training and modern equipment put themselves at risk during a water search, and the threat to recreational swimmers in natural bodies of water is much greater.
You should always match your swimming ability with the water you are entering, he said, meaning inexperienced or unskilled swimmers should swim where a lifeguard is present and where there are fewer dangers than in streams, rivers, ponds or lakes.
Younger swimmers are typically more prone to overconfidence in unpredictable waters and more often the victims of drownings, he said.

Reed said that with months of hot weather yet to come this summer she hopes people will realize there are better options for swimming and cooling off in Reading than entering the river.
“It's totally understandable why people want to swim there,” she said, “but please don't do it.”