Going into the game, the Iron made three changes from the side that visited Swindon Town, as Andy Butler, Kevin van Veen and John McAtee came in for Jai Rowe, Levi Sutton and Ben Liddle.
With three minutes played, there was an early corner to the away side. Billy Clarke swung it in, and the Iron eventually cleared through Rory McArdle, winning a throw-in in the process.
On six minutes, the Mariners picked up a free-kick 30 yards from goal, after a soft foul was given against Alex Gilliead. Clarke curled it to the back post for Harry Davis, but the defender headed wide of the mark.
After 10 minutes, the Iron looked to counter through van Veen, who laid the ball off to George Miller on the left-hand side, but the forward's cross was skewed for a goal-kick, with James Perch and McAtee arriving in the box.
With 15 minutes gone, Max Wright found Vernam on the edge of the Iron box, but as the latter's strike looked to trouble Rory Watson, McArdle put his body in the way to block, and the Iron cleared the danger.
Three minutes later, Waterfall tried to win a header in the Iron box, but the ball fell to his team-mate Vernam, whose shot was blocked. Shortly after, Clarke's low drive was well held by Watson.
On 21 minutes, George Miller knocked it past Luke Hendrie using his pace on the counter, and Anthony Driscoll--Glennon cynically brought him down, picking up a booking in the process.
There was another booking for the away side moments after as McAtee was brought down by a reckless Waterfall challenge on the edge of the area. Van Veen stepped up to take the free-kick, which dipped low to the goalkeeper’s left-hand side but went just wide of the post.
In the 27th minute, van Veen's corner aimed for Butler, who headed down towards goal. McKeown's fingertips then just reached the ball before the foot of Miller, who was waiting to pounce on a possible error.
McAtee did well tracking back five minutes later, clearing for a corner in the process. However, Clarke's inswinger was powerfully headed away by Iron captain Butler.
Not long after that, McAtee delivered a teasing ball from the right wing in search for the arriving Perch, but it was McKeown who came out on top, beating the Iron midfielder to the ball by a split-second.
With 37 minutes on the clock, Jordan Gabriel threw in a couple of step-overs to beat his man on the right, before firing in an overhit cross, aiming for Lewis Butroid at the back post. The ball went out for a goal-kick to the away side.
Three minutes after, Gabriel was on his toes to beat his man to the ball down the right flank. His clipped through-ball was latched on to by Miller, but the Iron forward's square ball to McAtee was well blocked, and the ball ricocheted out for a goal-kick.
The first chance of the second half fell to van Veen on 50 minutes, who broke through the Grimsby defence but was forced wide, and he couldn’t quite find the target from a tight angle.
With 52 minutes gone, Miller's hard work down the right earned the Iron a corner. Van Veen swung the ball in towards McArdle, but Waterfall was there to head away for a throw-in to the Iron.
Just a minute later, Grimsby took the lead through as former Scunthorpe youth product Vernam headed in from close range.
In the 62nd minute, Grimsby’s lead was doubled as Waterfall climbed to head into the net following Clarke’s right-wing corner.
There was then a Scunthorpe substitution, with Devarn Green coming on for Butroid. Soon after, Jacob Bedeau was yellow carded for a foul on the halfway line.
With 71 minutes gone, van Veen picked up a free-kick 25 yards from goal, after being held for a prolonged period of time. The Iron No 10 stood over it, and curled to Bedeau. The defender headed down for Miller, whose shot was blocked for a corner. From the resulting corner though, Green’s long range effort cleared the crossbar.
Shortly after, The Iron came forward again through McAtee and van Veen. The former played a ball across the box, which was turned behind for another corner. Van Veen's delivery was then cleared.
On 77 minutes, Bedeau floated a ball into the box and after pinball in the 18-yard area, the ball dropped to Green, but the forward's goal-bound strike was blocked by the Grimsby rearguard.
Ten minutes before the end, van Veen's marauding run towards the by-line earned the Iron a corner. The Dutchman's cross was cleared at the near post by a black and white shirt though.
Just two minutes later, Levi Sutton was shown a straight red card for a challenge on Elliott Whitehouse. It came just minutes after he’d replaced McArdle.
Soon after, Gilliead was booked for a foul on Vernam on the edge of the box, as the visitors looked to break.
Elliott Grandin took the resulting free-kick from 20 yards, with Butler blocking the initial strike, and Watson punching clear at the second attempt.
There were two more bookings in the closing stages, as Elliott Hewitt hacked McAtee down off-the-ball on a promising counter-attack, and picked up a yellow card for the foul. While Perch was then booked for a challenge on that Mariners player.
Scunthorpe return to action next Saturday when they travel to take on Colchester United (3pm kick-off).
IRON: Watson, Butler, van Veen, Perch, Gabriel, Butroid (Green, 64), Gilliead, McArdle (Sutton, 77), Miller, Bedeau, McAtee.
IRON SUBS: Lawlor, Songo’o, Rowe, Pugh, Liddle.
GRIMSBY: McKeown, Hendrie, Waterfall, Davis (Pollock, 45), Glennon (Tilley, 59), Hewitt, Grandin, Whitehouse, Wright, Clarke (Green, 73), Vernam.
GRIMSBY SUBS: Russell, Davies, Clifton, Benson.
ATTENDANCE: 6,855.
