Hundreds charged into the slightly-warmer-but-still-chilly Boston Harbor early Sunday afternoon, in an annual event raising funds to support programs along the harbor coast all summer long.

“Today, this is one of the best years,” said Save the Harbor, Save the Bay Executive Director Chris Mancini. “We got so lucky with the weather. It’s just cold enough to feel like you did something brave, but not so cold this was a misery. Last year was 18 degrees when we went in. That was the worst. But people seemed good now, I could tell from the smiles.”

The 16th annual Shamrock Splash, a polar plunge from East Boston’s Constitution Beach put on by Save the Harbor, Save the Bay, raised money for the Better Beaches Grant Program to plan free summer events and programs across beaches from Nahant to Nantasket.

Sunday’s event included music on the beach, chowder from the Daily Catch, lawn games, a costume contest and more.

“On March 9, this is probably the best weather you can get, so we’re very lucky in that sense,” first-time polar plunger Miriam ElKorchi said, before adding she was in “not long” but went up to her shoulders.

Standing in the cloudy, warmer weather, ElKorchi said she came out with a group to support the cause.

“On kind of a serious note, I was like, there’s a lot of bad stuff happening in the world, and I wanted to support a worthy cause,” said ElKorchi. “Just stuff that’s local.”

Grace VanValey, who’s participated for six years, said “it’s a fun shock, and then you’re jazzed for the rest of the day.”

“Last year we woke up, and it was pouring rain, and I think it was 12 degrees with wind chill, just kind of miserable,” said VanValey. … “I think the most fun part is after; everyone’s exhilarated and wants to hang. And last year, it just wasn’t that. But this year, it’s fun.”

Several people commented on the “impressive” costumes, noting the contest winner was dressed as Rose from Titanic, complete with the door she clings to in the water.

First-timer Laura Jacobs Beal said she the experience was a good surprise.

“I thought it was gonna be terrible, but it really was quite fun,” said Jacobs Beal, standing on the beach after the run. “I felt great after. I was like, I could do this more.”

Mancini said the water “felt pretty good” and is “always worth it.”

The organization was founded 40 years ago, Mancini said, when Boston had “300 million gallons of sewage a day, untreated, going into the water.”

“We now have the cleanest urban beaches in the country, here in Boston, which a lot of people don’t realize,” Mancini said. “So we started these programs to tell people that, and gradually evolved that so that you could break down barriers, who wasn’t going to the beach, and you could really help celebrate the really diverse cultures that we have here in Boston.”

The Better Beaches grant program supported nearly 200 events last year with over $300,000, according to the organization, expanding partnerships and creating programming for multilingual, queer, disabled and more communities in the region.

“Your summer calendar is about to be booked with free beach events,” said Maya Smith, Save the Harbor, Save the Bay’s director of partnerships and program development. “If you go to savetheharbor.org you can find free events almost every day. And again, we’re spanning the entire coast of Boston Harbor, from Lynn all the way down to Hull. There’s always something free, painting classes, workout classes, crafting groups. Anything that could tickle your fancy and bring you to the beach.”

Swimmers show off their get ups at the annual Shamrock Splash costume contest. (Libby O’Neill/Boston Herald)
Boston’s Christian Matyi plunges into Boston Harbor wearing colonial attire during Sunday’s Shamrock Splash. (Libby O’Neill/Boston Herald)