Former Mariners' defender Nigel Boogaard thought he had done enough to open the scoring with a powerfully-struck header after 15 minutes, but was denied by a diving save from Ryan who tipped the ball out for a corner.
While the possession statistics were in their favour, scoring opportunities were not. Adelaide were quick to seize on a misdirected pass in the 35th minute but Dario Vidosic couldn't capitalise on a two-on-one situation and skewed his shot off-target.
A fluent attack down the left flank late in the half was the Mariners' only real opportunity, but Pedj Bojic was unable to take advantage of some good work by Josh Rose and Ibini.
With so much at stake, the home side came out firing in the second term and found themselves in front just two minutes after the resumption.
Bojic delivered a perfectly-weighted cross which found Bernie Ibinin, and the youngster was good enough to steer his header past a stranded Eugene Galekovic.
It was the first of a flurry of chances for the hosts. Oliver Bozanic dragged his shot wide before a set piece from Michael McGlinchey cannoned off the post in the 57th minute.
Serginho van Djik went closest to a reply with a sizzling free kick clattering into the Mariners' wall.
Only a brilliant save from Galekovic prevented Patrick Zwaanswijk doubling the home side's lead on the stroke of fulltime.
