Northwave swimmer Melita Raravula, 16, has three top 10 rankings and another two top 20 rankings.
Her top 10 swims will be in the 100m butterfly, sixth, the 50m butterfly, seventh, and the 200m butterfly, eighth.
Raravula's top 20 ranked swims are in the 50m breaststroke, 12th, and the 100m breaststroke, 15th.
Fellow Northwave swimmer Freyah Ruri, 14, is 16th in the 100m backstroke and 20th in the 50m backstroke.
Other Northland swimmer ranked in the top 10 is 25-year-old Shane Smith, of Bay of Islands swimming club, who is ranked ninth in 50m breaststroke and 14th in the 100m breaststroke.
The other Northlander competing is 17-year-old Haydn Jurisich, of Northwave Swimming Club.
Whangarei's Cameron Leslie will also be competing at the nationals for his Auckland club, Laser Mt Eden.