Federal authorities arrested five people, including a father and two sons, who they said cultivated thousands of marijuana plants on state land on Kauai.
The marijuana farm is in an extremely remote area at the foot of Mount Waialeale, halfway up a ridge.
The case started with a tip to Kauai police, who went up in their helicopter and spotted thousands of marijuana plants from the air.
The people charged cultivated marijuana full-time, authorities said.
Images from federal video surveillance from July and August showed people cultivating marijuana plants in rugged, mountainous terrain in what is known as the "Blue Hole" area on Kauai.
The feds seized nearly 6,000 pot plants worth about $6 million on the street. It is one of the largest marijuana busts in Hawaii's history, officials said.
"The large amount of drugs involved in this investigation shows that this operation was organized and conducted by this group for profit," Hawaii U.S. Attorney Ed Kubo said.
The feds arrested and charged five people with manufacturing marijuana, including Edward H. Holland, 55; his son Robert Jason Bihm, Bihm's wife, Melissa Ann; Holland's other son, Ryan Edward Bihm; and Mark Steven Darling, 52.
"At one point, officers saw several of the defendants even smoking their harvested marijuana during their breaks from their labors," Kubo said.
The pot cultivation site is at the end of a remote valley, part way up a ridge, prosecutors said. It takes one hour each way to drive and then hike in, according to authorities.
"You're talking about a considerable effort to conduct this cultivation operation, and, more or less, during the growing season, you're talking about a full-time job," Assistant U.S. Attorney Michael Kawahara said.
Feds also seized six trucks belonging to the group.
The hillside marijuana farm has been used for at least several years, investigators said.
Authorities said they expect to arrest more people in "Operation Green Stream."
"We will continue to identify other members of this organization and take every penny that they earned illegally," said Tony Williams of the Drug Enforcement Agency.
The group members could get 10 years to life in federal prison if they are convicted. However, the man authorities fingered as the ringleader, Edward Holland, could get at least 20 years in prison because he already served a four-year sentence in another pot case.
Holland was convicted of marijuana distribution in 1991.