HALEAKALA NATIONAL PARK, Maui >> Well before dawn each morning, throngs of tourists from around the world make their way to Maui’s tallest peak, a dormant volcano, to see what Mark Twain called the “sublimest spectacle” he ever witnessed.

They drive up a long, winding road through clouds to an otherworldly, lava-rock landscape at 10,000 feet. Then they bundle up and take their place for a dazzling daybreak show.

“Just the sunrise from the top of the world — it’s pretty remarkable and incomparable,” Julia Grant of Mission, British Columbia, said on a recent visit after watching the sun peek out from the horizon and saturate the sky in endless shades of yellow, orange and red.

Over the past year the sunrise view from atop Haleakala — Hawaiian for “house of the sun” — has been attracting more than 1,000 people a day. The result, officials say, was a logjam of cars spilling out of the parking lots and onto the road, creating a safety hazard, and footsteps trampling sensitive habitat.

To address the problem, the National Park Service last week started requiring reservations and limiting the number of vehicles to the available parking spots, potentially cutting in half the number of early-morning visitors.

Sunrise viewing has long been popular at Haleakala, one of the main attractions at Haleakala National Park, despite morning temperatures that often dip into the 30s. Red soil and lava rocks dominate the summit, and only a few hearty plants have adapted to the harsh, high-altitude conditions.

The peak also is home to the nene, the Hawaiian goose, and colonies of spiders that feast on bugs blown in from the surrounding wilderness.

Overcrowding started becoming a problem roughly 15 years ago, park Superintendent Natalie Gates said. About a year ago it got worse, likely as more people learned about the stunning sunrise views from images shared on social media.

“If you ever went up there, you would see that fully half to three-quarters of our visitors who are watching the sunrise are either taking photos that they immediately broadcast to their friends or filming it,” Gates said.

The area at and near the summit has 150 parking spaces, but before the new system took effect, more than 300 rental cars and other vehicles often crammed onto Haleakala at daybreak. Drivers who couldn’t find a spot would park on the side of the road or on the road itself, blocking the way for emergency responders.

Though only 16 percent of park visitors come at sunrise, they account for 40 percent of the park’s emergency medical calls.

“It’s a dark place. It’s rocky. And when people are moving away from crowds and trying to go off trail, often frequently stumbling around on cliff sides in the dark, we see trauma cases, altitude cases,” Gates said. “We sometimes see cardiac and other cases.”

Straying humans also tread on seedlings and root systems of the Haleakala silversword, a rare, bushlike plant with thick leaves. And they can disturb the ground nests of the Hawaiian petrel, an endangered seabird.

Under the new system, only those driving to the summit between 3 and 7 a.m. need reservations, which cost $1.50 per car plus the $20 park entrance fee.

The system closes to sunrise viewers after the allotted 150 vehicles per morning have made their reservations. The proceeds will pay for administering the reservation program. People on guided tours won’t be affected, as tour companies fall under different regulations.

Reservations can be made up to two months in advance at the website recreation.gov.

The change will require adjustments from people who don’t normally plan ahead, said Carol Clark, Maui Visitors and Convention Bureau spokeswoman. But her agency contends the benefits far outweigh any inconvenience.