Visitors on the boardwalk pass one of the new anti-profanity signs on Memorial Day weekend at the beach on May, 24, 2014 in Ocean City, Md. (Bill O'Leary/Washington Post)

It’s that time of year again, when high school graduates from the Washington region descend on Atlantic shore towns for a final fling with friends: what is well known as Beach Week.

The long tradition of teenagers cutting loose in rented houses near the ocean leaves many parents on edge. Some ask students to sign pledges not to have overnight guests or house parties. Some bunk up at the beach themselves, so they can drop in unannounced.

Police in at least one popular shore town — Dewey Beach, Del. — say there might be some cause for optimism this year. Underage drinking offenses fell sharply last year, a trend they hope will continue.

But with the latest wave of just-­graduated seniors now at the shore, many families worry about possible perils: underage alcohol and drug use, teen driving and ocean swimming. All of them can lead to costly mistakes.

This week, a teenager who graduated from Montgomery County’s Paint Branch High School in 2013 died in Ocean City after being hit by a wave and pulled into a rip current. Authorities said currents can be dangerous and lack of swimming experience might have contributed. They said they do not suspect alcohol was a factor.

“I’m nervous, and I will be until they all get back safe and sound,” Suzy Slyn Davis, a North Potomac parent, said just before students from her daughter’s high school set out for the trip last weekend.

Many high school students see Beach Week as a rite of passage, the highlight of their school career and the best chance to celebrate before friends part ways for college or other pursuits.

Among parents, there is tension. Many have not forgotten the images that were all the buzz last fall, when Maryland Attorney General Douglas F. Gansler (D) was photographed at his son’s Beach Week party in Delaware, looking on amid the revelry, with teens dancing on a nearby table.

Gansler, who was a month into his bid for governor, later said he should have done more to investigate apparent underage drinking. But he also spoke of some of parenthood’s essential conflicts, including how much to let them go and how much to rein them in.

Part of the question involves alcohol. Some parents accept underage drinking as a fact of adolescence, and they impose rules prohibiting driving after drinking, for example, to reduce the danger. Others say they don’t tolerate teen drinking at all, which they point out is neither legal nor safe.

Still others see Beach Week as an exception, with college just around the bend.

“I think it’s a risky thing,” said Therese Gibson, PTSA president at Montgomery Blair High School, who advises families to give Beach Week a lot of thought. For students, she said, “it’s their first taste of freedom, with problems that could follow them into adulthood.”

A number of parents insist on Beach Week limitations, including shorter stays, fewer roommates and adult chaperones.

Bonnie Sharbaugh, a Bethesda mother of four, said her son stayed four nights in a rented condo, with four boys she knew. She did not worry because of the kids involved, but would not have wanted a large group situation. “If you get 15 kids in the house, I’m sorry, that’s a party house,” she said.

Davis, of North Potomac, said it made a difference that her daughter is particularly responsible and that her group was staying in a family’s home in Ocean City, “not in the midst of the mayhem.”

“We’ve had many discussions in our house about it,” Davis said.

In Fairfax County, Steve Treger said his senior is headed to the Outer Banks with friends for a late-June Beach Week. Beach Week tends to vary according to graduation and exam schedules.

“It’s a big thing, they’ve been looking forward to it probably from the first day of their senior year of high school,” he said.

Treger said he remembered his own Beach Week fondly and “like it happened yesterday.” Still, as a parent, he said, there is natural concern. “You get a little worried,” he said.

Police from shore towns now travel to a number of schools in Maryland, Delaware and Pennsylvania months ahead of time to acquaint parents with the hazards of the Beach Week party scene and the problems that go with a lack of adult supervision.

Dewey Beach Police Sgt. Clifford Dempsey warned Montgomery parents of problems at a meeting in late January.

“Your kids at some point will end up at a house party were there is alcohol, lots of it; there’s drugs, lots of it; there’s fights; there’s sex,” Dempsey said. “Everything you can think of happens when that sun comes down, and that’s when we have most of our problems.”

Still, he said, the warnings might be getting through: In Dewey, a major destination for high school students, underage alcohol offenses fell by nearly half, to 56 for the Beach Week period last year, compared to 108 for 2012.

Some parents were persuaded by the warnings.

Jessica Brown, a Montgomery mother of two, said she got the message that students were not entirely welcome and that it was a “total time of craziness,” with significant risks. She and her husband told their high school senior she could not attend.

But Brown said theirs has seemed a lonely choice, with many parents giving the go-ahead. Maybe some feel that sense of tradition, she said. But she argues parents should not look the other way in the face of underage parties.

“If parents would just stick together,” Brown said, “it’d be so much easier.”

Ann Gallagher, a Bethesda parent, said her graduating senior decided to go camping at a Maryland state park with several high school friends rather than join the crowd at the beach. Gallagher says she feels fortunate to have escaped it.

“I think Beach Week is a recipe for disaster,” she said. “But I would not necessarily have prohibited her from going.”