BANGOR — Sixty years ago, a couple of unexpected guests drew thousands of people to the local waterfront. Traffic stopped. Children hung over bridge railings to get a glimpse. But this was no concert.

On April 26, 1954, “a strange, white creature” was spotted swimming in the Penobscot River, according to Bangor Daily News articles. Fascinated crowds lined the banks of the river.

For about a week, the white thing, which usually appeared for short stints as a hump in the water, moved up and down the river between a former Bangor bridge and the old Bangor Water Works dam.

It took awhile for the newspaper to definitively identify the mysterious swimming thing. After a few days of speculation and disagreement — shark, seal, porpoise, very large cod, submarine — a University of Maine professor named Horace Quick was able to get close enough to recognize it as a beluga whale. Belugas are white and reach an average adult length of 12-14 feet.

It had wandered up the Penobscot, probably in pursuit of a pool of smelts or some other stock of fish. Whales sometimes make their way into the river, but for them to come this far up was extremely unusual.

Steve Robbins was a 9-year-old living on South Main Street in Brewer at the time. He remembers his family going down to a pier near Connor Coal & Wood Co. to get a glimpse. No one was allowed on the pier, but it was crowded that day, as were both riverbanks. He remembers his older brother, who was 29 at the time, going out in a boat, possibly to get a closer look.

“I’m not sure what he would have done if he’d caught up with it,” Robbins laughed.

A few other curious people in small boats pursued the whale as well.

Liz Plumer Ashe of Bangor was just 6 years old at the time, but she remembers leaning over a railing alongside her father.

“I remember him pointing down at something white in the dark water and saying ‘There! That’s it,” she said Friday.

The whale became known as “The Penobscot River’s Moby Dick” and eventually it was joined by a smaller companion. These whales became the subject of a children’s book, “The Day the White Whales Came to Bangor,” written by Gerald Hausman. The book describes the whales jumping and playing around in the water, but witnesses didn’t see much if any of that, just the occasional white hump emerging from the water.

After a few days, however, some Bangor residents and officials became hostile toward the creatures, according to news reports. Some residents expressed concern that the whales would hurt local salmon populations. Others talked about harpooning the whales. Still others allegedly shot arrows at them and harassed them in boats, according to news reports.

Fed up with the traffic problems the spectacle caused, local police officials reached out to the Sea and Shore Fisheries Commission to see how best to get rid of the whales so the city could move on.

The suggestion? Shoot ‘em.

The public didn’t take kindly to that recommendation, which was made on the fourth day of the whales’ visit. “Literally hundreds” of calls poured into the Bangor Daily News and Bangor Police Department calling for a stay of execution, according to news reports.

Apparently the whales somehow caught wind of the plot against them. On May 2, they fled back toward sea and were gone.

Since then, there has been at least one false whale-sighting alarm in the vicinity. In 2007, traffic ground to a stop along the Penobscot River after drivers and pedestrians lined up to squint at what they thought was a whale just north of the former Bangor Water Works site. Brewer firefighters launched a hovercraft, only to find the whale was just a plastic tarp that got stuck on some rocks.

To commemorate the brief and unusual visit of the real whales, the Bangor Historical Society and Maine Discovery Museum are planning an event around 4:30 p.m. Friday, May 2, according to Matt Bishop, interim director and curator at the historical society.

The Maine Discovery Museum is displaying a series of whale-visit-inspired watercolors by Maine artist Francis Hamabe, who died in 2002, as well as news clippings from the Bangor Daily News. Those items are on display on the first floor of the museum, to the left of the reception desk.