Not much has been happening in a roughly 50-foot-deep crater spanning 10 acres in Kalaeloa since the Navy created the hole around 70 years ago, mining coral limestone for building runways at Barbers Point Naval Air Station.

Kiawe, banyan and hale koa trees have grown in the old quarry.

Next month, though, a creative new use will start up in the gigantic forested pit, where outdoor fun seekers can ride a long rope swing, traverse high wires, pedal electric mountain bikes, sail along zip lines and drive off-road go-karts.

The activities are the creation of former Hawaii tour activity seller James Owen, who is slated to open Coral Crater Adventure Park to the public Dec. 3.

“There’s nothing like this out here,” said Steve Colon, senior vice president of Hunt Cos., a firm that acquired much of the former military base from the Navy and is leasing the crater to Owen. “We think it’s a fantastic amenity for the West Oahu community.”

Owen, who spent about $2 million establishing the park on 35 acres between Enterprise Avenue and Midway Road adjacent to an FBI headquarters building, said he’s targeting both local residents and tourists as customers. He guesses the split might be 50-50.

“I don’t know,” he said. “It’s hard to say.”

Indeed, there is nothing quite like this attraction in Hawaii.

Local government officials, Hunt employees and others gave the park activities a tryout Friday as some finishing touches like bathrooms and go-kart seat belts were being installed.

The park has been about six years in the planning, starting with Owen’s search to find a spot for a zip-line ride. He said a real estate agent helping him suggested a property in Kapolei. Owen said he couldn’t think of anywhere in the area with potential, but after his agent led him to the crater’s edge, he saw how he could do a zip line and more.

“I said, ‘Oh, this will really work,’” he recalled.

John Bond, a local historian involved with protecting historic sites at Kalaeloa, said making such use of the quarry didn’t strike him as inappropriate.

“We had no problems with it,” Bond said. “It seems to me like a generally good use for the land.”

The roughly 3,600-acre military installation was closed in 1999, and various private, federal, state and city entities are slowly reusing and redeveloping parts of the former base that include housing, commercial uses, a Coast Guard facility and White Plains Beach.

For the adventure park a paved parking lot and picnic area were added topside, and an Oregon company called Synergo built six zip lines and a 60-foot-high wooden structure with four stories that support two climbing walls, a rope swing, a high-wire challenge course and something called a Quickjump that requires a person to step off a plank 50 feet up and free-fall for about 10 feet before a belay line controls the remaining descent.

“You are going to be given a countdown,” advised Nolan Shamayim, a former Synergo employee now managing the tower with his wife, Alina. “When you give us the head nod and you are sure you want to do this, you’re going to get a ‘three, two, one, step.’ On ‘step’ you’re going to step out.”

Betty Dumas, a Hunt office manager, needed extra cajoling to step off.

“I’m chicken,” she said after getting the initial countdown and staying on the platform.

From the ground, state Rep. Andria Tupola (R, Kalaeloa-Ko Olina-Maili) encouraged Dumas. “It’s two seconds of scary,” Tupola said. “You can do it. It’s going to be fine. Betty, you can do it.”

Dumas took the drop and said afterward it wasn’t that bad. “I mentally told myself I can do it, and I did it,” she said.

For the off-road go-kart and electric mountain bike rides, old dirt roads around the bottom of the crater provided natural yet dusty trails for rides led by guides. There is also another 12 acres at normal ground level and a route to the beach for riding the bikes, which require pedaling but are assisted by an electric motor, Owen said.

Owen said food trucks will serve customers and that an imu and fire pit are also planned.

Prices range between $20 for doing the quick jump twice and $200 for a full day of all the activities. Kamaaina discounts will be available.

The park will operate from 9 a.m. to 6 p.m. However, Owen said he plans to operate a Saturday night tour where visitors ride in an old German six-passenger jeep and use laser rifles to shoot at volunteers emerging from the woods dressed as zombies.

Owen also would like to do zip-line rides at night. One other zip-line option will allows riders to shoot zombie mannequins hidden in the trees with the laser rifles.

“I found zip lines when I’ve done them in other places not to be exciting enough,” he said.