They will be up against New Zealand's best and this meet is by far the biggest swimming challenge they have had.
O'Keeffe will swim the 200m, 400m and 800m freestyle events, kicking off with the shorter distance this morning in the Westwave Pool in Henderson.
She is ranked in the top 20 800m swimmers in the country.
Couper competes in the 50m, 100m and 200m backstroke, with the 50m her first event this morning. She is ranked in the top 28 200m backstrokers in New Zealand.
Safely through this meet, the pair are part of an eight-strong Wanganui Swimming Club team heading to the New Zealand Age Group Championships in Wellington in two weeks.