State officials announced Monday that plans are underway to expand Oahu’s Diamond Head State Monument, offering a more pedestrian-friendly entrance to the crater as well as opening up additional properties to the public.

The state Department of Defense has agreed to transfer previously closed lands, including the Kapahulu Tunnel, to the state Department of Land and Natural Resources, for public use, as part of an overall effort to reduce is own footprint within Diamond Head Crater.

Currently, the only public access to the crater is through the Kahala Tunnel, a narrow, two-way pathway which pedestrians share with cars, trolleys and other commercial vehicles, creating a safety issue, state officials said in an online story map prepared for DLNR by PBR Hawaii.

The Kahala Tunnel, built in the 1940s, is often overcrowded, and visitors often walk onto the adjacent roadway shared by vehicles.

The availability of the Kapahulu Tunnel opens up the opportunity to create a separate entrance into Diamond Head Crater for pedestrians only, without vehicles.

“Diamond Head, or Leahi, is an iconic monument recognized and associated with Hawaii around the world,” said Division of State Parks Assistant Administrator Alan Carpenter in a news release. “The state DOD’s transfer of these areas to DLNR- Division of State Parks, creates a unique opportunity to improve access and the visitor experience to Diamond Head.”

In addition to offering a safer pedestrian pathway, the makai side of the Kapahulu Tunnel — originally a mule-powered rail line used to transport materials for the fire control station to Diamond Head’s summit — offers great, panoramic views. This new pathway would also connect to the Fort Ruger Pathway.

The Diamond Head State Monument remains one of Oahu’s most popular attractions and logs more than a million visitors to its summit trail annually.

“We could not have foreseen how many visitors we were going to have today,” said Carpenter. “That’s the reality. We’re also finding that people get (to the crater) by different means now — Uber, Lyft, shuttles, biking, and it’s an easy walk from Waikiki. Unless we impose visitor limits, there’s really no slowing down.”

Plans to transfer the lands have been in the works for at least a year and a half, according to Carpenter, with the overall goal of improving visitors’ experiences within Diamond Head Crater.

A Diamond Head State Monument master plan, drafted in 2003 and updated in later years, outlines these initiatives. Since then there have been a few changes, including the construction of the Culinary Institute of the Pacific on the slopes of Diamond Head.

The changes are expected to be implemented in the next year to two at a relatively low cost, he said.

Down the line, the state envisions creating a visitor drop-off circle for commercial vehicles near the Diamond Head Road and Makapuu Avenue intersection, which would reduce traffic through the Kahala Tunnel. Visitor parking would also be added outside the crater, with a shuttle to key landmarks in and around the crater.

Ultimately, the long-term goal is to restrict the Kahala Tunnel entrance to staff and those with disabilities, while limiting parking to the crater’s exterior. The majority of visitors entering the crater would then go through the Kapahulu Tunnel.

Diamond Head State Monument is jointly managed by the state DOD and DLNR State Parks.

DLNR State Parks offers comfort and recreational facilities inside the crater, alongside structures used by the DOD and the Hawaii Emergency Management Agency, which are delineated by security fences. Earlier this year the state demolished DOD Buildings 301 and 304, but it plans to retain its Emergency Operations Center and other properties.

The state DLNR, meanwhile, invites the public to offer its input through a six-minute questionnaire at surveymonkey.com/r/DiamondHead.

Hawaii State Parks is offering those who participate the chance to win two giveaways of merchandise from the Diamond Head Visitor Center each day through Jan. 14. PBR Hawaii will contact the winner via email for delivery of the prizes.

Diamond Head State Monument is open from 6 a.m. to 6 p.m. daily except for holidays. The entrance fee is $5 per car or $1 per person for pedestrians, by cash only.