Dolphin avenged a home defeat from earlier in the season as they cut loose against second-placed Clontarf at Castle Avenue.
The Cork club's full-back Eamon Mills scored a brace of tries with his back-three colleague James Kiernan running in his fifth score of the Ulster Bank League campaign.
Dolphin were stung by a late try against Cork Constitution last weekend, and with the benefit of a first half wind they set the early pace against 'Tarf.
Steve Ford's men took the lead when centre John Gleeson touched down following good build-up play by forwards Chris Rowe and Ryan Murphy, whose terrific break opened up the space.
Ireland Under-20 international Murphy was a key figure for Dolphin who were missing several players who were away on duty with the Munster 'A' squad.
Barry Keeshan landed the conversion and Mills, racing through from inside his own half, crossed the whitewash soon after, making it 12-0 and giving the north Dubliners plenty to do.
But 'Tarf put those sloppy opening 10 minutes behind them when impressive young winger Michael McGrath broke through for his 12th try in Division 1A this season.
Richie Lane added the simple conversion from in front of the posts, before busy scrum half David Shanahan and captain Evan Ryan, who created an opening with a terrific sidestep, put flanker Tom Byrne over for a second seven-pointer.
Andy Wood's charges led 14-12 up to half-time and they moved seven points clear on the resumption, a Ryan charge down leading to Shanahan sniping over for an unconverted effort.
But the points dried up for 'Tarf despite the elements being behind them. Dolphin lifted the tempo in the final half hour, showing a clinical edge as they decisively ran in three more tries for an excellent bonus point win.
Despite losing experienced prop Christy Condon to injury, two quick-fire tries from former Ireland Under-20 captain Niall Scannell and Kiernan steered Dolphin to their bonus point.
Mills added his second try of the afternoon to confirm Dolphin as winners, while 'Tarf gained some consolation with a late 'show and go' try from departing full-back Matt D'Arcy.
Referee: David Wilkinson (IRFU)