They go swimming

Kat and Keira entered into the surf. The water was cool and refreshing. Keira breathed a sigh of relief. Sure, it was tough going to the beach with her absurdly proportion sister, but she was happy to enjoy the water. She waded out deeper until she was about waist deep in the water.

Keira saw a wave coming. She dove in, passing under the break. She popped out of the water, now fully wet, shaking her hair off. She was surprised though as the next wave was already coming. She'd never swam here, and wasn't prepared for the pattern of the waves. She dove back under the water before she could take a breath. Her lungs burned as she passed under the next wave, then emerged sputtering. Unfortunately the waves apparently came in three, and this one caught her straight in the face!

Keira was totally disoriented as she went head over heels underwater. Her cheeks bulged as she struggled to figure out which way was up. Then she popped up gasping for air and half drowned. She spent a full thirty seconds regaining her breath. Then she noticed something. Something felt different. Something on her body. What could it be?

She looked down. To her utter shock and horror she saw her own topless torso. She gasped at the sight. She was topless! No... worse then that! Under the water she could see her lower half was bare. She was naked! Totally naked on a public beach!