Even on Martha’s Vineyard, where art gallery openings are reliably free of suits and swanky dresses, it is still uncommon for an opening to draw a sizeable crowd clad in bathing suits — sunbathers literally on the way home from the beach. And rarer still for a bank to open its lawn on a Friday evening, after business hours, to play host. Yet bare-footed art openings at the Chilmark branch of the Bank of Martha’s Vineyard have been a regular occurrence for at least 30 years.

No one seems to know quite how they started or when. “As long as I’ve been here, there’s been art,” said branch assistant manager Kim Klaren, who has worked at the bank for the past 23 years. Mrs. Klaren thought the openings began under former branch manager Margaret Maida. “Oh, they’ve been going on forever,” Mrs. Maida said when asked. Mrs. Maida worked at the bank for 29 years before she retired two years ago. She suspected Gardner Drew, a bank officer back when it was Martha’s Vineyard National Bank, as the man behind the first few openings.

Mrs. Maida began at the bank straight out of high school; the openings already were anticipated events. “There used to be art galleries right here in Chilmark,” Mrs. Maida said of her first years working in the town. Menemsha alone had two galleries — the Berresford Gallery, currently Menemsha Blues, and the Cooper Gallery, owned by Betty Cooper. In those days, the branch was only open from June 15 until the first Saturday after Labor Day. Slowly, about 15 to 20 years ago, the bank began extending its season. Today, it is open year-round and the art rotates more frequently than the seasons.

The openings were sporadic at first. An artist interested in showing would approach the bank, hold an opening and, when the next artist came calling, the art was switched. About 25 years ago, the exhibitions became more consistent, as more and more artists began vying for space on the bank’s walls. Mrs. Maida gave the openings a schedule — booking a new artist every two weeks. “There was a waiting list for a couple of years,” she admitted.

Island photographer John Wightman was one of the first artists to make the space a regular showroom. “I had shown at a number of galleries both on and off the Island before this one,” he said recently. His first show was more than 20 years ago, he guessed: “I used to do a week in October, then it was November, and then I moved closer to the prime time.” For years now, Mr. Wightman has been the only artist with two shows at the bank. He has one in the summer months and then, when the season slows down, he hangs his work for the duration of winter.

“It’s a very versatile group that comes in — it’s better than Boston,” Mr. Wightman said of the crowds. “It’s a great outlet, an awesome outlet, for people trying to get exposure. Plus, it’s close to home. I can be there in 10 minutes,” said the Aquinnah artist.

Not much has changed at the bank since Mr. Wightman began showing there. The artists still hang their art themselves on fishing line, send out the invitations and bring in their own drinks and snacks. The crowds have remained diverse.

Already the bank is booked next year from the beginning of May through the end of October. This summer the branch ramped up its schedule. For more than 20 years, the bank held one opening every other week in season; this year, they held one a week, hosting about 20 artists, said teller Ashley Bruce, who has taken over Mrs. Maida’s responsibilities organizing the openings,

“We have a lot of people return year to year,” said Ms. Bruce. The bank also is opening its doors to emerging artists. Six new artists joined the roster this summer. One was Island photographer Kelley DeBettencourt. The opening was the first of her career. “It was a great learning experience,” said Ms. DeBettencourt, who set up her own wine and fondue to welcome friends, family and curious art appreciators.

She said the bank staff went above and beyond to help. Weeks before her Sept. 7 opening, Ms. Bruce called to invite Ms. DeBettencourt to the bank to watch another photographer hang his work. The experience helped the emerging artist plan her own layout.

Not only did Ms. DeBettencourt hang large prints, she also brought small cards to sell, something Ms. Bruce said is common. “A lot of times, people will bring more than just their art,” she said. “They will bring calenders, prints and cards, so that the opening is attainable for everyone. People may not be able to buy a piece of art, but at least they can take home something memorable.” Sometimes, artists do not make any of their work available for purchase. “Some people just want their friends to see their art,” Mrs. Maida said.

When selecting the artwork, the people at the bank are not picky. “The only requirement is that you have an account with us,” Ms. Bruce said. The space is free, and the bank takes no commission. Ms. Bruce looks forward to the openings, held on Friday evenings between five and seven. “It’s a nice way to socialize and get to know the residents,” she said.

“It mimics the local scene around here,” said Mrs. Klaren, who helps Ms. Bruce select the artists. “There are so many artists up here and so much interest in art.” The art attracts people to the bank who normally would not stop by, both women said, and often the bank receives telephone calls inquiring about the artists even when no opening is scheduled.

For Vineyarders, the openings provide an up-Island venue for art. For the bank employees, the shows spice up the workday. “I enjoyed being able to look at different things on the walls, rather than just one painting hung in the same place year after year,” Mrs. Maida said.