Jonathan Crowe was once again the match-winner for the Hawks, who won by five wickets with five overs to spare to move up to fourth spot on the ladder.
Chris Prescott (3-20) set the standard with the ball, ripping through the Mariners top order to have the defending champions reeling at 3-8.
Crowe then led from the front, hammering four boundaries and four sixes on his way to 88 not out.
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READ NOWDavid Thomason smashed 23 not out to put the finishing touches on another fantastic win for Gosnells, who have defied the odds so far this season.
Gosnells faces winless Mount Lawley next Saturday in a two-day fixture at Breckler Park.