Striker Tony Bedeau scored twice for the Gulls, his second goal coming only a minute from time and even then both teams could have won it in a frantic finale.
Leaders Wycombe are the only team to beat Russell Slade's Mariners on the road this season, and it was easy to see why as they started fast.
Andy Marriott did well to keep out an early volley from Town's beanpole defender Ben Futcher and the visitors took the lead after only six minutes.
Grimsby debutant Junior Mendes found right-winger Andy Parkinson with a raking crossfield ball and Parkinson finished coolly from 15 yards.
It took Torquay most of the first half to get going, but when they did they looked quite capable of worrying their in-form opponents. Right-winger Martin Phillips was the dangerman.
It was from his cross that Bedeau put a good chance over after an eight-man move in the 27th minute.
Seven minutes later Bedeau equalised for the first time, turning in the box and firing home from ten yards from a low cross by left-back Anthony Lloyd.
In first-half stoppage time another Phillips cross saw Kevin Hill head against the bar and over.
Grimsby had a Gary Jones goal disallowed for a push by the veteran striker as he went to head home in the 59th minute, but from then on it was nearly all Torquay.
Bedeau twice, James Sharp and the pacy Jo Kuffour all went close, but just when Torquay looked the likelier winners, Grimsby broke out and regained the lead.
In the 81st minute Torquay failed to cut out Tom Newey's long-range free-kick and Futcher dived to head home from eight yards, but Torquay weren't finished.
A minute from time Phillips laid on yet another cross from the right, Hill nodded the ball back at the far post and Bedeau headed home from point-blank range.
Even the, both sides could have snatched victory, Rob Jones twice denying Kuffour with last-ditch tackles and Marriott saving with his legs when former Torquay striker Martin Gritton was through.