Welcoming the Mariners to McDonald Jones Stadium on Saturday, the Jets were ruthless against their at-times hapless foes, taking an early lead through Aleksandar Susnjar, then piling on the goals after Storm Roux's 39th-minute red card.
The defeat left Mark Jackson's side nine points outside the top six with two games remaining, ending their run of fairytale back-to-back championships at two and forcing them to watch the playoffs from home for the first time since 2019-20.
Five points outside the top six with just three games to play and already having announced that coach Rob Stanton will not be returning, the Jets are also unlikely to play finals, but they secured derby bragging rights for the first time since December 2022.
Clayton Taylor ran the show, the 21-year-old assisting Susnjar and Daniel Wilmering's goals and inducing Mariner skipper Trent Sainsbury to turn the ball into his own net on the stroke of halftime.
He then made it 4-0 with a long-range laser in the 50th minute.
Kota Mizunuma set up Eli Adams for the fifth in the 73rd minute, and the youngster grabbed a second in the 92nd, ensuring the six-goal margin equalled the Jets' 8-2 win in 2018 for the heaviest in the rivalry's history.
Reflective of the Mariners' evening, the red card to Roux came just eight minutes after he came on as a replacement for an injured Mikael Doka, lashing out with an elbow following a tussle with Callum Timmins.
Outshot 22 to to four, the Mariners failed to force Jets keeper Ryan Scott to work all evening.
