Bournemouth went ahead through Lee Bradbury after six minutes but then Grimsby scored through Jamie Clarke, Ryan Bennett and Robert Atkinson to take a stranglehold on the game.
Darren Anderton pulled one back for Bournemouth, who then had Scott Guyett sent off for a second bookable offence, but the Cherries pushed forward and Bradbury scored his second a minute from time to secure a share of the spoils.
Bournemouth's opener came when Atkinson misjudged a long ball and Bradbury took possession before unleashing a fierce strike into the bottom corner. Grimsby equalised in 42nd minute when a Danny Boshell corner reached Clarke and he fired a half-volley into the top corner.
Skipper Bennett put the Mariners ahead just a minute before the break when he met Tom Newey's cross at the far post and headed over visiting goalkeeper Shwan Jalal. Another header brought Grimsby's third shortly after the hour mark when Atkinson met a Nick Hegarty corner and nodded home from a central position.
Bournemouth narrowed the deficit in the 78th minute with a close-range strike from Anderton after Mariners keeper Phillip Barnes had pushed away a Jason Pearce header. Then Bradbury pounced for the equaliser, latching onto a cross from Shaun Cooper and firing home from close range.