State officials said overall that the new reservation system for Diamond Head State Monument went relatively smoothly Thursday — the launch’s first day — but could have gone better.

The state Department of Land and Natural Resources said an estimated 40% of people who showed up at Diamond Head during early morning hours had not made reservations, which are now required for out-of-state visitors.

A long line of waiting cars stretched from the vehicle tunnel to the park entrance at Diamond Head Road before gates opened at 6 a.m., according to officials. A bottleneck formed at the tunnel near the parking area as staff checked the reservation status for people in vehicles as well as those arriving by foot and on bicycle.

“Everyone came at once, as usual, for the 6 a.m. hike,” said Division of State Parks interpretive technician Cassandra Springer in a video release. “Everyone came at once and not everyone had reservations. Actually, the majority of people didn’t have reservations, which made the line very long.”

The line eased after the initial backup, with a mostly peaceful transition, officials said. Honolulu resident Steve Tam, a regular morning hiker on the winding climb of about 1 mile to the summit, said that when he arrived at the park at about 6:15 a.m., admissions proceeded steadily. Reservations and admission fees are not required for residents, who must show a Hawaii driver’s license or state-issued ID in order to enter.

Despite extensive media coverage and efforts by visitor industry partners, many visitors from the mainland were unaware that reserv­ations are now required to visit Diamond Head. Springer said additional weeks to months of outreach efforts may be in order.

Some out-of-state visitors who were turned away Thursday were frustrated because it was their final day of vacation, and they were unable to make reservations. State parks staff were prepared for this, she said, and directed those visitors to nearby attractions and hikes.

Overall, people were nice about the new rule, Springer said, and some visitors who walked in were able to use their smartphones to make reservations.

The intention of the reservation system is to reduce congestion at the iconic park, also known as Leahi, thereby keeping it in line with a state initiative to better manage tourism and its impact on natural resources.

With a reservation system, the number of visitors can be spread out throughout the day instead of being concentrated within popular morning hours. DLNR’s goal is to limit the number of park visitors to 3,000 per day and no more than 300 per hour. This, in turn, will offer visitors a better-quality experience at Diamond Head, officials said.

In 2020, entry fees for Diamond Head increased to $5 per person for walk-ins and $10 per vehicle for parking. The new system relies on QR codes that the parking vendor scans to confirm reservations, eliminating the exchange of cash at the entrance.

The reservations can be made 14 days in advance at gostateparks.hawaii.gov/diamondhead in two-hour slots for those entering by vehicle and in one-hour slots for those entering by foot. The earliest reservations are available at 6 a.m., and the latest at 4 p.m.