Sycerika McMahon, 17, qualifed for the Olympics in the 100m breaststroke at the European Swimming Championships in Debrecen, Hungary, in May.
McMahon came fifth in the final of the Europeans and as a result secured her place at London 2012.
The Portaferry, Co Down, woman also won silver medal in the 50m breaststroke at the same event, in a time of 31.27 seconds.
McMahon swims for Leander club and holds a world ranking of seventh.
First in Olympic action on 29 July in the heats. Start time is 10am.