Carter Galley scored 37 points, including a tying 3-pointer in the closing seconds of regulation, and the Mariners (3-0) dominated the extra session to complete a comeback win over the Windjammers (2-2) in Rockport.
Galley got 29 of his points after halftime as Oceanside, the reigning Class A state champion, erased a 15-point deficit.
Zeb Foster added 20 points and Cohen Galley scored 16.
Nolan Ames led Camden Hills with 25 points. Will Duke followed with 17.