Britain won gold in the women's rowing quadruple sculls final for the first time at the Vaires-sur-Marne Nautical Stadium on Wednesday.
Netherlands took the silver medal, while Germany secured the bronze.
Team GB pipped the Dutch to victory by just 0.15 seconds despite trailing them for the entirety of the race until the final metre. A photo finish awarded GB with the gold.
"It doesn't get bigger than this. It's just really overwhelming," Lola Anderson said after the race.
Great Britain began to close the gap between first and second in the final 500-metres but it looked like the Dutch had built up enough of a lead to take gold.
Hannah Scott became the third athlete from Northern Ireland to win an Olympic gold in Paris alongside her teammates Anderson, Lauren Henry, and Georgie Brayshaw.
"We got to 250 [metres] to go and I could sense we were coming back, so I was like, 'Guys, now, we're going now,'" Henry said.
"And then I called it again about 150 metres to go, I was like, 'We can do this.'
"I kind of knew we'd crossed the line first but we had to wait to see, and when I saw 'GBR, 1' come up it was amazing."
GB's men finished fourth in the men's equivalent race with the Netherlands taking the gold. Italy and Poland took the silver and bronze respectively.
The British quartet Tom Barras, Callum Dixon, Matthew Haywood and Graeme Thomas finished in a time of five minutes and 46 seconds, two seconds away from the podium.