She also dominated the dynamic dives, reaching depths of 143m and 152m respectively on a single breath.
These dives require the competitor to reach their depth and return to the surface under strict rules about not losing consciousness, even just a momentary "blackout".
"I didn't expect to be ready to break a record at this competition. It's the start of our indoor season and I have not yet reached my peak," said Nevatt.
"But the static felt great, I was really relaxed and clear headed the whole way through and was able to stay calm and just enjoy being in the water."
Competing at Porirua's Arena Aquatic Centre, Hamilton's Sam Barnes, 59, was third overall and first male.
Rounthwaite trains at the Wanganui Splash Centre and also in Palmerston North.