The gang accessed the containers through the floor of a mobile home near the village of Ballyvourney.
Gardaí say it is the first bunker-style growhouse of its type found. They described it as “very sophisticated”, with its own power and water supply.
Armed with a search warrant, members of the Cork West Divisional Drugs Unit, raided the growhouse shortly after 7pm last Tuesday.
They found about 150 plants in various stages of growth, which have an estimated street value of €100,000.
Three men, believed to be in their early to mid-30s and from Eastern Europe, were arrested.
Two were being detained at Bandon Garda Station and the third in Macroom Garda Station under section 2 of the Drug Trafficking Act, 1996.
The growhouse was concealed under the mobile home in a woodland clearing at Derreenaling — about 3km south-west of Ballyvourney, near the Cork/Kerry border.
“This wasn’t done with a spade and shovel. Machinery had to be used to dig out the site for the containers,” said a senior Garda source.
He added it was the first underground growhouse of its type he had seen.
“We were used to mainstream republicans in the past and now dissident republicans using underground bunkers for hiding arms, training purposes, and hiding people. But we haven’t see this type of concealment with growhouses.”
Gardaí cordoned off the growhouse and yesterday morning started a full analysis of its contents. It is the second major growhouse seizure to occur on the Cork/Kerry border in past few days.
Last Thursday night, gardaí from Kanturk seized 204 cannabis plants in various stages of growth and about 1kg of processed cannabis worth in the region of €170,000.
The cannabis plants were found in sheds outside a family home near the village of Rathmore, Co Kerry.
A number of members of a family were in the house when gardaí raided it. There were no arrests at the time.
However, a Garda spokesman confirmed yesterday that a mother and son had since been arrested in connection with that investigation. “They were released without charge and a file is to be prepared for the DPP.”
Meanwhile, in an unrelated drugs seizure, gardaí arrested two men in their 40s following the discovery of cocaine, cannabis resin and cannabis herb worth €20,000 on the northside of Cork City.
Elsewhere, gardaí last night arrested two men, seized a number of stolen vehicles, and uncovered a cannabis growing facility in Ballycoolin, Dublin. The cannabis was worth about €125,000.