The thrilling high dives into Boston Harbor take every ounce of courage.
"I'm actually scared of deep water and heights," said diver Ellie Smart.
Smart is one of the 24 divers in this weekend's Red Bull Cliff Diving World Series competition in the Seaport District.
"I do it because that feeling you get after you do something you just really don't think you're capable of doing is just the best feeling in the world," said Smart.
The diving platforms were just installed Wednesday afternoon on the roof of the Institute of Contemporary Art.
"It's like Superman flying over the city of Boston," said diver Jonathan Paredes. "It's kind of cool."
Divers will be twisting, flipping and somersaulting. Men will dive from about 90 feet high, and women from 68 feet.
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"It's absolutely terrifying," said Smart.
"It's very scary," Paredes said. "I think it's a lot of pressure, a lot of nerves, fear. We're scared every time we go there."
The best cliff divers in the world are on the first stop of their six-stop world series.
Boston is the only U.S. location, so it's home turf for Smart.
"I'm so overwhelmed with gratitude to be able to do what I love and what I train and work so hard on in front of my friends and my family in my home country with my home crowd," she said.
Boston holds a special place in the worldwide competition.
"Boston is a city that understands sports," said Red Bull Cliff Diving World Series Director Orland Duque. "There's big teams here, there's big following, lots of tradition, we want to take a little bit of it."