BELLA THORNE O Captain, My Captain ... YOUR SEE-THROUGH TOP IS BOMB

Bella Thorne's not lost at sea -- she's exactly where she wants to be ... and wearing the appropriate nipple-freeing attire.

Bella channeled her inner David Lee Roth by rocking a captain's hat and a flaming hot shirt out in Hollywood Saturday night ... and added a see-through white top for her own personal touch.

She was with a new dude too -- not Blackbear or Scott Disick -- but rather "The Young and the Restless" actor, Max Ehrich.

We can only say  ... Rock on, Bella.