To reach their wedding venue, Austin O’Reilly and Iulia O’Reilly crossed a swaying suspension bridge, trying not to glance down at the glacial river below. With each step, the bridge shook under the weight of people and yaks. Mr. O’Reilly, 25, had seen similar bridges in the 2015 movie “Everest.” Now, he was on that titular mountain with his fiancée: walking a precarious bridge, crossing jagged moraines and traversing rocky terrain on a nine-day trek to the Everest base camp.

As terrifying as the bridge was, there was no turning back. “You’re just hanging on for dear life and knowing that your wedding is at the other end of this trek,” at an altitude of 17,600 feet, Mr. O’Reilly said.

The couple lives in New York and met in 2019 through mutual friends at Seton Hall University in New Jersey, bonding over their love of the outdoors and travel. When looking for a wedding venue in 2022, nothing felt right. “My dad jokingly was like, ‘What about Everest?’” Ms. O’Reilly, 26, said. The idea took hold and came with an added benefit: It would be cheaper than an American wedding.

“We really wanted something that would challenge us and represent our love for each other” said Mr. O’Reilly, an accountant at Deloitte.

On May 22, the couple reached the base camp with Ms. O’Reilly’s parents and two of Mr. O’Reilly’s friends. The 10-minute ceremony was accompanied by the distant rumble of avalanches. “Just you, your beloved and a higher power up there,” said Ms. O’Reilly, a researcher at Fox.

The bride wore a gauzy white dress, and the groom wore a suit; they both wore hiking boots. “With the backdrop of the icefall and the glaciers, hearing avalanches in the distance, you have this really powerful moment — and you’re also deprived of a lot of oxygen,” he said.

Their trek was hosted by Laura Gravino and her husband, Ian Taylor, who own Ian Taylor Trekking. For the 13 years they’ve been married, the couple have facilitated several trekking weddings. Ms. Gravino said that, for her, the appeal of an adventure wedding lay in its contrast with big American weddings, which can often be complicated and expensive.

The O’Reillys are one of many couples having an adventure wedding, taking their venue out of the realm of the ordinary. These adrenaline-heavy events trade ballrooms and historic estates for mountains and lagoons, pushing couples to physical extremes and setting pulses racing even more than they’d already be.

An adventure wedding is also an opportunity for a couple to partake in activities that brought them together. Haley Badenhop and Owen Leeper met at a sand volleyball court in Jackson Hole, Wyo. “He’d been like, If you want to go on an adventure, let me know,” Ms. Badenhop, 36, said. A month later, they did just that for a full week — cliff jumping, boating, hiking and paddle boarding. “By the end of that week, I was like, Is this what my life could be like?” she said.

Mr. Leeper, 38, is a professional skier, and Ms. Badenhop often incorporates mountains into her work as a mural artist. The couple sometimes spend entire days skiing together. “Living in Jackson, you kind of have to get good at skiing,” Ms. Badenhop said. And so the idea of a ski wedding at Jackson Hole Mountain Resort was born, something that had never been done before at the top of Rendezvous Mountain, located in the southern Teton Range of the Rockies.

The couple and their guests took a tram to the peak and gathered on an expanse of snow. Ms. Badenhop’s niece, wearing a snowsuit with a tutu, threw dried flower petals as she walked down the snowy aisle. After exchanging vows, the couple changed into ski boots. “We kept our attire on, and everybody cheered us on as we skied down,” she said. “It’s a ‘black run,’ so I had worn a strapless backless dress, and I taped it to myself.”

The wedding party skied or took the tram down for a champagne party at the bottom. It was everything Mr. Leeper had dreamed of. “She’s skiing down in her wedding dress and willing to do this with me — it’s going to be a great partnership for life,” he said.

As more couples choose daring wedding experiences, vendors are rising to the occasion. Brittany Hamilton, a photographer in Fort Collins, Colo., who specializes in elopements, has been rock climbing for six years. Her proficiency in rope systems and scaling has uniquely intersected with her career in photography.

“I always take my camera with me, and I learned how to ascend a static line to be able to shoot on the side of cliffs,” she said. When Ms. Hamilton’s rock climbing friends began marrying, they expressed an interest in capturing that side of their relationships.

“I think there’s something about climbing where you’re really trusting your life to your belay partner, your climbing partner, and that lends itself to relationships in a lot of ways,” she said.Ms. Hamilton makes sure that couples she works with have the necessary proficiency.

She said that an elopement climb shouldn’t require a couple to push themselves. “Climbing in a dress adds this whole factor of billowing fabric around you,” she said. “While you’re in your wedding attire, we’ll probably be climbing on easier stuff.”

But the realities of a rock climbing wedding — and all adventure ceremonies — can lend themselves to sweet wedding photos: “moments of them gearing up, putting on their harnesses, double-checking each other’s knots,” Ms. Hamilton said. One of her favorite parts to photograph is “when you’re climbing, before you take off from the ground, you’re always double-checking that your partner is safe,” she added.

For Ariel Slusher-Miethe, 32, an adventure wedding was a way to step outside her comfort zone. Before meeting Alex Miethe at a Las Vegas nightclub they both worked at, she had never pictured herself marrying. But after their engagement, she began considering a wedding that would take place underwater — another place she’d never imagined herself before. She’d always been afraid of the ocean.

“Honestly, it was kind of like an ode to him,” she said. “This is how much I love you — I’m going to face my fears and go underwater and scuba dive.”

Ms. Slusher-Miethe, an aesthetician, took scuba classes leading up to their underwater wedding, which took place in December 2019. They flew to Cozumel, Mexico, where they dived beneath the aquamarine waves. The couple said “I do” using signs, and their 15 guests watched from above while snorkeling.

An unconventional venue can create unique logistical hurdles: The couple had to tie the wedding rings to their boxes. “When you’re underwater, if the ring falls out, it can go anywhere,” Mr. Miethe, 35, an E.M.T., said. “The kiss was hard, too, because you’ve got to take out the regulator, hold your breath, kiss real quick and bring it back.”

Afterward, the couple took photos while dancing and twirling underwater. Tania Nacif Iñigo, the photographer in Cozumel who shot their wedding, had learned to dive to supplement her photography almost 30 years ago. “You have to be an advanced diver because you have to control your buoyancy, be aware of the current and be comfortable with your gear,” she said. “Your life depends on it.”

Shooting underwater weddings, which Ms. Nacif has done about 10 times, allows her to combine her passion for outdoor photography with her work as a wedding photographer.

For Mr. Miethe, a highlight of the wedding was seeing his wife overcoming her fear. “She’s nervous when she’s down there, but the second she gets up she’s like, ‘Oh my God, that was amazing,’” he said. “That was an awesome thing to see, that transformation.”