When Vickie Henry took a stroll on an Assateague Island beach last week, she never expected to see a massive sea creature briefly emerge from the water: a giant manta ray.

“I originally went to Assateague because it was a beautiful day and I needed outdoor time,” Henry, of Salisbury, MD. told Fox News on Wednesday. With her dog, Maggie, by her side and her camera in hand, the photographer and owner of Maggie and Me Photography took to the island to capture images of its wildlife, such as monarch butterflies and wild ponies.

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“But, on Assateague, you never know what you might see, so I'm always on the lookout,” Henry said.

Shortly before leaving the island, Henry said she took Maggie for a walk along the beach, where a woman approached the duo and asked to pet the pup. At that moment, while standing and looking out at the ocean, “I saw a big splash directly out in front of us,” she said, noting the splash was “quite a ways out in the ocean.”

“My first thought was that it was a whale,” she said. But from so far away, it was difficult to tell for sure. When the creature breached for the second time, Henry was quick to snap a series of photos.

Later, when she returned and uploaded the images to her computer, she was surprised to learn it was “not a whale but a giant oceanic manta ray,” she said.

Officials with the Maryland Coastal Bays Program confirmed to the Salisbury Daily Times that the creature was indeed a giant manta ray, not to be confused with the stingray. While the two are related, “manta rays do NOT have a tail ‘stinger’ or barb-like stingrays,” the Manta Pacific Research Foundation says, adding stingrays “dwell on the ocean bottom, but manta rays live in the open ocean.”

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A manta ray's wingspan can reach 20 feet or more, according to the conservation group SEEtheWILD. The creatures, which can weigh as much as 5,300 pounds, according to the National Oceanic and Atmospheric Administration (NOAA), are found “worldwide in tropical, subtropical, and temperate bodies of water and is commonly found offshore, in oceanic waters, and near productive coastlines,” according to NOAA.

Sandi Smith, an official with the Maryland Coastal Bays Program, told the newspaper spotting a manta ray is “rare.”

“The beauty of Assateague never fails to amaze me,” Henry said. “I go as often as I can find the time and I am never disappointed. Having Assateague so close by is a privilege and I enjoy capturing and sharing its treasures whenever I can.”