Jersey's men's 4x100m medley relay team produced one of the top performances of the 2015 Island Games as they broke the previous record by over two seconds.
The team of Ian Black, Cameron Donaldson, Tom Gallichan and Harry Shalomon were four seconds quicker than Guernsey who took the silver medal.
Gallichan also took gold in the 200m backstroke with teammate Nathan Corrigan winning bronze.
Jersey's golden night was completed when they won the women's 4x100m relay.
Gemma Atherley, who also won 400m freestyle silver, teamed up with Susanah Phillips, Olivia Pollard and Beckie Scaife to finish 0.41 seconds ahead of the Isle of Man.
"Today's been our best day of the week so far and those relays at the end were really special," Jersey swimming coach Nathan Jegou told BBC Radio Jersey.
"Even when you've got people like Ian Black and Tom Gallichan in there with that experience, to smash the Island Games record by two seconds is no mean feat."
Guernsey's Courtney Butcher won gold in the 200m backstroke, her second gold medal of the games after she won the 100m backstroke on Tuesday.
Earlier in the night her teammate Tom Hollingsworth had won silver in the 100m individual medley, with Jersey's Black in third place.
Hollingsworth went on to win bronze in the 50m butterfly behind Cayman Islands' Olympic swimmers Brett and Shaune Fraser
Meanwhile the men's 100m freestyle saw the same order of medallists as two years ago, with Guernsey's Miles Munro finishing third behind Brett and Shaune Fraser.