Universal Studios, SeaWorld and others are equipping rides with tighter restraints to ensure that small children and others can’t wriggle out from seats. The new seats can be a tight squeeze for some visitors, and riders have said that staff have declined to seat them on some rides because of their size. 

“Our first priority is always the safety of the guests and the employees,” says

Jim Seay,

president of the ride manufacturer Premier Rides, which has built roller coasters for the Six Flags, SeaWorld and Universal Studios parks. “We balance that with a very focused effort to make the rides as accessible as possible.”

Universal has drawn criticism online from theme-park fans who say the design of the slow-moving ride is exclusionary when, according to government statistics, the average waist circumference measures 40.5 inches for men and 38.7 inches for women. The park faced similar criticism in 2021 because seats on its The Secret Life of Pets: Off the Leash ride had dividers making it difficult for some larger people to fit.

Universal’s warnings, as well as test seats outside rides, are intended to help visitors, says Jeff Polk, senior vice president of resort operations at Universal Orlando Resort. 

“We want our guests to know what they should expect and what they should look for when they get to one of these attractions,” Mr. Polk says, adding that the park welcomes feedback.

Ride hacks

Some theme-park fans say the potential restrictions for rides such as Bowser’s Challenge are emblematic of the stress and anxiety many plus-size visitors can feel at theme parks. Several social-media groups offer advice on navigating theme parks for these visitors; one Facebook group focused on

Disney

has more than 84,000 members.

Dean Paris, a Facebook group moderator and insurance underwriter from central Illinois, scours YouTube videos to see how people get on the vehicles and negotiate the restraints. “If it looks like it’s just absolutely not going to work, I don’t waste my time,” he says.

Travel agent Sarah Goff says she has been on several rides in which she might not have fit were she a few pounds heavier.

“It seemed like the theme park ride vehicles were getting smaller, and I was getting bigger,” she says. Mrs. Goff, who lives in Lima, Ohio, says she feared embarrassing her family if park staff told her she couldn’t fit on a ride. In March, she is launching a website with advice for plus-size visitors to Universal parks.

Mrs. Goff, 47, says she wears compression leggings at theme parks, partly because their texture allows her to sit farther back in rides’ seats, giving her more room for safety restraints. Other strategies travelers use to fit on rides include pulling seat belts out before sitting down, or pulling down on a ride’s lap bar as they sit to improve their leverage.

Tighter safety, tighter seats

Before joining the line for a ride, park visitors can try test seats placed at ride entrances to check whether the restraints will accommodate them. 

Visitors say the tryouts can be awkward, and some told The Wall Street Journal that the models can be less forgiving than the actual seats on the ride. Universal says differences can be a result of wear and tear on test vehicles, and adds that it is exploring ways to provide testers with more privacy.

While Disney classics such as Pirates of the Caribbean or It’s a Small World have no restraints, rides today are often designed for what ride experts call “100% containment,” meaning there is no way for a person to exit or be injured midride.

Stricter safety standards requested by insurers and worries about visitor lawsuits influence ride design, says Jason McManus, a principal at Thinkwell Group, an experience design company.

“What might seem like a fairly benign ride still has to take into consideration that a very young child might need to be contained,” Mr. Seay says. Children might not understand the risks of exiting a ride in motion, and even a slow ride involves complex and potentially dangerous machinery. There is also the problem of people trying to jump off rides in an attempt to film a video for TikTok.

Yet rides with full containment might not fit larger adults. “If you size every seat for the largest possible person, you’re guaranteeing that a smaller child cannot ride,” says Jim Shull, who worked for over 30 years as a Disney Imagineer, a term for

Walt Disney Co.

’s theme-park designers.

NBCUniversal, part of

Comcast Corp.

, says it is looking at ways to update rides to fit more guests.

Retrofitting a ride to accommodate more riders must be done carefully. After a 14-year-old boy from Missouri died after falling off a ride at a Florida entertainment complex last March, an autopsy found that he exceeded the ride’s weight limit. An investigation found that adjustments made to the ride’s safety harness contributed to the accident.

Some rides, such as the Incredible Hulk Coaster at Universal’s Islands of Adventure park in Florida, have some seats designed for larger-size guests. And other recent attractions at theme parks stand out for fitting people with different body sizes, such as a new roller coaster based on the Guardians of the Galaxy film franchise at Disney’s Epcot park. Disney declined to comment.

“It is the most comfortable ride vehicle I’ve ever seen, and it accommodates a lot of people,” Thinkwell’s Mr. McManus says. 

Write to Jacob Passy at jacob.passy@wsj.com