The beleaguered Mariners are now facing a second successive relegation after a spineless display against mid-table Blackpool.
Injuries and suspension meant that Nicky Law's boys were much weakened and they were simply not good enough to trouble Blackpool, who strolled to their seventh away win of the season without moving out of second gear.
The goals were well taken. The first from striker John Murphy, who finished off a fine move on 19 minutes and the second from Danny Coid, who headed in when Grimsby failed to clear their lines from a corner on 53 minutes.
After that there was no way back for Grimsby and the remaining 30 or so minutes were played out in a soulless atmosphere in which players and fans alike were resigned to the drop into Division Three.
Grimsby were forced to field a makeshift strike partnership with defender Paul Warhurst returning to the striking role of his earlier days.
But Blackpool could argue that they had to make a late switch when midfielder Martin Bullock injured his hamstring in the warm-up.
Ironically his replacement Sean Hessey only lasted ten minutes before he too was injured to be replaced by Jamie Burns.
But neither setback affected Blackpool who did not have break sweat to take the points and the 300 or so travelling fans enjoyed their coast to coast day out, although the match itself was entirely forgettable.
With this result and the other fixtures Grimsby have slipped to third from bottom and with just four games left relegation is staring them firmly in the face.
Their remaining home games are against fellow strugglers Rushden & Diamonds and Brentford and they travel to Stockport who are also in trouble and Tranmere, who they face on the final day of the season.