Paris Jackson -- Vacations With Mom ... in Treatment For Years

Paris Jackson looked healthy and happy vacationing with her mom in Hawaii ... but MJ's daughter still has a long road ahead of her -- we're told the treatment will last years.

Debbie Rowe and Paris mugged for the camera during the trip ... as you know, Rowe lost contact with Paris after she divorced Michael Jackson, but the 2 reconnected a little over a year ago and are now extremely tight. Rowe speaks constantly with Paris -- who is at a boarding school in Utah.

As for Paris' treatment ... our sources say she's riddled with so many problems she's almost certainly spending several years at the facility ... where she is getting intensive counseling.