HONOLULU (HawaiiNewsNow) - They call it the Halawa tar pit.
It's a ten-foot deep deposit of thick oily material that covers an area the size of basketball court near the Halawa Animal Quarantine Station.
No one knows who dumped this gooey substance beneath this state parking lot. But it's been around for decades and no one seems to be doing anything about it.
"This poses a risk to the environment, the health of people and animals," said environmental activist Carroll Cox.
"There should be some aggressive effort to clean it up."
The state, which conducted studies of the tar in 2003 and 2006, said the materials don't pose any hazards to nearby residents and the environment.
They said they've left it alone for years because cleaning up the site would cost more $120,000.
But during a tour of the site, Cox showed us how the tar often bubbles up on hot days and spills into a nearby storm drain, which empties into the ocean.
There are other environmental concerns.
"You'll see the plover in here foraging, feeding and resting and you'll see other birds," he said.
Cox said several state workers have contacted him about their health and safety concerns.
"Employees here say they're afraid it may be a sinkhole underneath when you have this much oil bubbling up and flowing down," he said.
The tar has been on the property since the late 1960s, when the state acquired the land from the U.S. Navy.
The Navy also owns the nearby Red Hill Fuel Farm, which has leaked hundreds of thousands of petroleum products over the past few decades.
"That's sufficient for us -- if nothing else -- to ask the Navy to embrace this and come up here and spend some money and do some studying," he said.