What did Percy need to do in order to survive a plunge into the river of Styx?

To survive a plunge into the River Styx, Percy Jackson needed to avoid being fully submerged in the water, as it could make him invulnerable but also strip away his mortal essence. He had to rely on his instincts and the help of his friends to navigate the dangers of the river and find a way to avoid its lethal effects. Additionally, he needed to maintain his focus and strength, as the river could disorient even the strongest of heroes.