Sycerika McMahon has qualified for the women's 100m freestyle at May's European Swimming Championships in Debrecen, Hungary.
McMahon's time of 1:09.42 in winning the 100m freestyle at the Irish Swimming Championships and Olympic Trials was a second inside the European qualifying time.
The 16-year-old, a European Youth Olympics medallist in Tampere in 2009, went on to claim the women's 400m freestyle.
It was the highlight of a night that promised much following an encouraging morning where two Irish records were broken.
Melanie Nocher still needs to shave a second off her women's 200m backstroke record set this morning in order to make it to London.
In the morning heats, the Ards starlet recorded a new Irish record time of 2:11.71, three-hundredths of a second inside her previous national standard.
But in bidding to repeat the act in tonight's final, Nocher won in 2:11.81.
Bethany Carson set a new Irish record this morning in the women's 100m butterfly, breaking the 16-year-old record of Michelle Smith by one-hundredth of a second.
The triple Olympic gold medallist's time set at the European Championships in Vienna in 1996 was narrowly edged out of the record books by the 20-year-old Lisburn swimmer.
But Carson could not beat her new mark of 1:00.58 in her evening swim where she was crowned national champion.
Carson is now 0.32 of a second outside the European Championships qualifying time, but is delighted to have wiped one of the oldest records off the map.
"To break Michelle Smith's record is something special," she said.
"I was going for it, but wasn't sure if I was going to get it in the heats. I want to go even faster and hope I can.
"I am going to try and go for the European mark. I talked to my coach Paul Donovan before and Peter Banks (national coach) to try and relax the stroke so it just felt a lot more relaxed. I knew it was good, but wasn't sure how good."
Among the other national champions crowned so far this evening include Nicholas Quinn of Castlebar in the men's 100m breaststroke, Jane Roberts of Kilkenny claimed the women's 50 breaststroke, with Karl Burdis of Portmarnock victorious in the men's equivalent.
Will Downing, National Aquatics Centre