A young entrepreneur has started a new business in Boothbay Harbor.

Christie Gillies, 17, from Cape Elizabeth and Boothbay Harbor, is mixing up and selling her product, Seaside Smoothies, at Mine Oyster.

“There was no place in Boothbay Harbor to get a good, healthy smoothie,” she said. “One of my favorite places in Portland is Maine Squeeze. It’s an awesome smoothies place, and I wanted something like that. I go there all the time.”

Gillies’ mother, Kim, said her daughter had been thinking about selling smoothies for a while. “She was joking that if Joe Tassi ever decided to stop running his business, (Schooner Lazy Jack Cruises) out of Pier One, she’d like to use his little ticket office on the wharf between McSeagull’s and Mine Oyster for a smoothies takeout stand.”

The schooner business is still being run out of the little “shack,” but that didn’t deter Gillies. She started thinking about an area on the ground floor of Mine Oyster that was vacant during daytime hours. Over the winter, the then-high school junior wrote a business proposal to present to Mine Oyster owners Ralph and Elena Smith. They were impressed.

“Christie is a great girl,” Ralph Smith said. “She called me with an offer to do her smoothies at the restaurant. She had a business proposal, a menu, a product list, pricing – the girl really had her act together, so how could I say no.”

Gillies spent a lot of time over the winter testing recipes and researching costs of ingredients.

At the beginning of July, Smith provided her with a bar space on the ground floor, with big windows overlooking the harbor. Gillies started mixing up smoothies, using fresh and frozen combinations of blueberries, strawberries, raspberries, mango, pineapple, spinach, orange juice, Greek yogurt and soy milk, and the results are tasty, and healthful.

The Smiths have added the Seaside Smoothies to the menu at Mine Oyster, so customers can order them with their meal. “I deliver them to the tables when people order them,” Gillies said. “Or they can come down and get them to go.”

Leah Akeley, who works at Boathouse Bistro, has been a regular customer since the business opened. She has a smoothie for breakfast almost every day. She even has one named for her. “Christie asked me if I’d like her to make me a special one.” The Leah’s Special is a smoothie made with blueberries, raspberries, mangoes, spinach, vanilla, banana, Greek yogurt and soy milk.

“There is an entrepreneur in her,” Elena Smith said of  Gillies. “She is a sweetheart. She’s nice and kind, and she puts that kindness in her smoothies. That’s the main ingredient.”

The business is open daily from 11 a.m. to 4 p.m. There are spaces with stools at the bar, or you can take the smoothies to go.

Gillies also plays drums in a jazz band around the harbor and in Cape Elizabeth.