She tried to reach the surface, but the waves were too agitated and pushed her back down each time. It got worse and worse until one of the waves sent her too deep to continue.
When all hope seemed lost, Uni's hand pierced the surface. She prayed for a miracle to get her out of there. Luckily for her, a hand seemed to catch her out of nowhere, pulling her out of the water during an oncoming wave!
This could only have been done by Nepgear, of all people.