Zac Purchase and Mark Hunter won Great Britain's first ever lightweight Olympic rowing medal and made it gold.
The lightweight double scull completed an unbeaten season as they eased ahead with 600m gone and held off Greece. World champions Denmark were third.
There was disappointment for GB's lightweight four - the defending world champions - who finished fifth.
But Team GB ended the Olympic regatta as top nation with six medals in all - two gold, two silver and two bronze.
It bettered their Athens haul of four (one gold) and their conservative pre-Games target of four medals of any colour.
On Sunday there were also silvers for the women's quadruple scull and men's eight.
BBC OLYMPICS BLOG
"We've had an excellent regatta," said Team GB's rowing leader David Tanner.
"Twenty-three athletes won medals which is more than half the rowing team and we've had our best results in a long time."
Hunter had to receive medical attention after clinching gold - his first in international rowing, eight years after he first joined Great Britain's senior squad and 13 years after his first junior appearance.
"I'm in a bit of a daze," he admitted. "National anthem, flag it's a dream come true."
Purchase, who was holding his partner upright, added: "It was unbelievable.
"We knew they would come back but we put the work in early so we could hold on at the finish."
Hunter's father Terry, who coached his son as a youngster, was clearly overjoyed.
He told BBC Sport: "He's worked 15 years. When he got his first international vest, he said, 'My dream is to be on that podium with a medal,' and he's won gold."
In the following race, Great Britain's lightweight four were unable to match the double's feats.
Richard Chambers, James Lindsay-Fynn, Paul Mattick and James Clarke were in third place at the half-way mark but faded as Denmark defended their Olympic title.
"Right now we feel really down but we did everything we could," said Richard Chambers.
"To be honest we had a good race - a good, clean race and it just wasn't good enough."
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