In ideal conditions, the hosts who were first to score, out-half Rob Guerin kicking a routine penalty in the fifth minute.
There then followed a ten minute spell in which the Dolphin pack established a stranglehold on proceedings and blitzed their opponents for 14 points.
A series of close-in scrums culminated in a penalty try in the 12th minute and, spurred-on by the score, the visitors wasted no time in doubling their tally.
A delightful touchfinder from Barry Keeshan took play deep into Shannon territory and from the ensuing maul captain Niall Scannell touched down.
That score snapped the hosts into action. Only resolute Dolphin defence kept Shannon from capitalising on their territorial advantage, but when visiting lock Chris Rowe was sin-binned for not rolling away Guerin cut the gap to eight.
Shannon’s revival continued after the break, despite the concession of a Keeshan penalty in the 46th minute.
Moments later, Munster centre Danny Barnes had the ball stripped from his grasp in midfield, but it broke kindly for Shannon full-back James Loxton to pick up and set off on a scintillating 60m sprint to the line.
Guerin converted impressively, but that was to be as good as it got for The Parish.
Keeshan steadied the Dolphin ship with a 9-point salvo just after the hour mark; two penalties sandwiching a sweetly struck drop goal.
By now, Shannon’s frustrations were taking their toll. Talismanic lock Fergal Walsh was soon followed to the sin bin by No.8 John Shine and a simple lack of numbers led to Dolphin’s third try in the 75th minute.
Possession in the Shannon 22 was spun wide to right wing and, with defenders sucked in, the ball was worked back to the left touchline where tighthead prop Christy Condon dove over.
Now chasing the bonus point, Dolphin came in waves. An audacious crossfield kick from loosehead prop James Cronin very nearly led to a Chris Rowe try at the death but the two forwards weren’t quite in sync and the chance was lost. Dolphin head coach Steve Ford admitted: “You’d always take that coming to Coonagh. Our record here in recent years hasn’t been great but we were clinical.”
Scorers for Shannon: J Loxton try; R Guerin 2 pens, conv.
Scorers for Dolphin: N Scannell, C Condon try each; Penalty try; B Keeshan 3 pens, drop goal, 2 conv.
SHANNON: J Loxton, C O’Donnell, E Maloney, R Mullane, C Cunnane, R Guerin, M D’Arcy, G McNamara, D Casey (capt), K Griffen, S McCarthy, F Walsh, E McLaughlin, J Murphy, J Shine.
Replacements: N Horan, D Fitzgerald, J Sherin, M Leonard, C O’Neill.
DOLPHIN: E Mills; J Kiernan, D Barnes, C Bohane, H Fleming, B Keeshan, C Bannon, J Cronin, N Scannell (capt), C Condon, C Rowe, D O’Shea, R O’Herlihy, M Cronin, B O’Callaghan.
Replacements: J Cleary, J Leahy, D O’Mahoney, E O’Shaughnessy, R Scannell.
Referee: M Patton (IRFU).