BRUNSWICK — It was an ambush that others expected.

Mt. Desert Island High entered the Class B girls’ swimming and diving championship Monday with fewer swimmers seeded near the top than Cape Elizabeth and Greely. But the Trojans turned in several surprising performances to win the state title at Bowdoin College’s LeRoy Greason Pool.

MDI totaled 379 points to win its sixth championship – and its first since 2014. Greely (333) finished second, and three-time defending champion Cape Elizabeth (288) came in third.

The Harper twins, Olivia and Haily, paced Morse to fifth place, with four individual victories and a tie for first with Cape Elizabeth in the 400-yard freestyle relay.

Olivia won the 100 butterfly in 54.99 and broke her meet record in the 100 backstroke with a time of 54.28. She won the butterfly, for the third straight year, by 5.25 seconds, and the backstroke by 5.06 seconds, earning Performer of the Meet honors.

“I really, really wanted to do better than my junior year. Always shooting for better times,” said Harper, who will swim for the University of Tennessee.

Haily Harper, who said she is still deciding on a college, won the 200 individual medley (2:10.84) and the 100 breast stroke (1:06.16).

Cape Elizabeth senior Caroline Mahoney was also a double-winner, in the 50 freestyle (23.54) and 100 freestyle (51.43), and was part of two winning relays – the 200 medley and the 400 free.

“Every meet is different, and I wasn’t sure how this was going to go, but I’m happy,” said Mahoney, who will swim for Bucknell.

Other individual winners included Greely’s Emma Cyr (5:31.42 in the 500 freestyle), MDI’s Cecilia Saltysiak (2:00.27 in the 200 freestyle) and Hyde diver Emma Stone (374.85 points).

Saltysiak’s effort was typical of the Trojans. She entered the race as the sixth seed but shaved 6.35 seconds off her time, winning in 2:00.27.

When assessing a meet, coaches and fans rely on best times during the season to figure out who is favored. That was impossible with the Trojans.

“We had this (state meet) as our focus all year,” MDI Coach David Blaney said. “We came off (our usual) events in our conference championships. We trained for this, so I’m not surprised at all.”

In the 50 free, 11th-seeded Ruby Brown finished third for MDI. Freshman Zoe Horton, seeded 14th in the butterfly, finished third. Freshman Nina Rozeff, seeded 18th in the 100 free, finished eighth. And, so it went.

“That’s typical MDI. It wasn’t surprising,” said Greely Coach Rob Hale, whose team won the North Southwesterns last week in an emotional effort to unseat Cape.

“Our Holy Grail was last week. We spent a lot of energy. We swam pretty well (Monday), but not as well as last week.”

Greely led after four events, 130-118, but had no divers. MDI, with two divers, took a 141-130 lead after that event and never relinquished it.

MDI was seeded to score 31 points in the butterfly, but the Trojans placed third, fourth, 10th and 12th, collecting 43 points. It was the same in the 100 freestyle. Instead of an expected 16 points, MDI scored 32. Eighth-seeded Ruby Brown, a senior, finished third, helping the Trojans open a 216-169 lead over Greely.

In the 500 freestyle, Greely’s Cyr, a freshman, and junior Blake Wescott each knocked 15 seconds off their seeded time to go 1-2.

“That was big. Those two kids gave us a boost,” Hale said. “Then we needed to win the 200 free relay, but it didn’t happen.”

Instead, the MDI relay team of Rozeff, Callan Eason, Daisy Granholm and Brown stayed just ahead the whole race, winning in 1:43.43, with Greely (Kyla Moroney, Abby Hollis, Cyr and Jaehee Park) second in 1:43.81.

Cape’s winning medley relay team consisted of Mahoney, Ali Bragg, Emma Frothingham and Bella Eremita. The Capers’ 400 free relay team had Bragg, Eremita, Grace Taylor and Mahoney. Along with the Harpers, Morse’s 400 free relay had Natalie Emmerson and Fiona Cashman.

NOTE: Because of a forecast of snow, meet officials announced that the Class B boys’ meet on Tuesday will start approximately 30 minutes earlier than planned, at 10:30 a.m.