Elsa loses control over her powers; when Anna tries to calm her, they both get trapped in ice peril, with watery tentacles ravishing them, ice gags and so on. Especially delicious if it happened during swimming.

Anna popped her head out from the water and waved to her sister. "Come on in."

Elsa hesitated, staying on the river bank. "I don't know."

"Don't worry," said Anna. "It's fine."

"Alright." Elsa experimentally dipped her foot in the water. Anna splashed her with water. "Don't do that!"

Anna rolled her eyes. "Just get in the water you big baby."

Elsa finally jumped into the river, doing a graceful swan dive into the water. She soon emerged from under the water. "God that's hot. Feels like we're in a sauna."

"Not really," said Anna. "It feels normal."

"Trust me, it's boiling," said Elsa.

"Whatever you say." The two of the began to swim around. Anna would occasionally splash water at Elsa.

"Stop that!" said Elsa as Anna splashed her again.

"Make me." Anna began to splash water at Elsa with a vengeance.

"Stop it right now!" said Elsa.

Anna laughed. "Like I said, make me."

Elsa held up her hands and froze the next wave of water Anna splashed at her. The chunk of ice floated down the river. "Don't make me do that again."

"Don't make me do that again," said Anna in the most mocking voice she could produce.

She continued to splash water as Elsa, who continued to freeze each wave. "Come on Anna, this is serious."

"This is serious," said Anna.

"Real mature," said Elsa.

"Real mature." Anna made sure to make this last sentence as whiny as possible.

"I'm leaving." Elsa began to swim back to the riverbank.

"Wait, don't leave," said Anna. "I've got something for you."

"What?" said Elsa.

"Just stay right there." Anna ducked under water and when she emerged, she spat a stream of water at Elsa. The stream hit Elsa right in the face. Out of instinct, Elsa froze the stream. This was a mistake. Before she realized what had happened, Elsa had frozen the water around their mouths. Elsa struggled to break the ice on her mouth, but to no avail. She wanted to scream, but she couldn't. She looked to Anna, who was also trying to break out, but like with Elsa, she had no success. The ice on the surface of the river froze, trapping the two sisters. A current came, pushing them down the river. Soon they had floated all the way down the ocean. Elsa tried to kick her legs, in an attempt to steer the block of ice to land. Even though they couldn't talk, Anna seemed to guess what Elsa was doing began kicking also. However, without the ability to communicate, the only thing she accomplished was to cancel out her sisters efforts.

After awhile, Elsa began to feel something brush against her foot. At first she thought it was a fish, but then she felt it moving up her leg. The thing felt like a tentacle. Her eyes widened. There were octopi here. She looked at Anna, who had a similar look on her face. The octopus was attacking her too. Elsa tried to kick the tentacle away, but it was relentless. It reached her thigh and pushed up her skirt. She could do nothing as the tentacle felt her clit. Elsa felt something on the tentacle sucking on her. The tentacle then began stroking Elsa's slit. If she was being perfectly honest, Elsa was actually enjoying the sensation of the tentacle moving up and down her. She wanted to groan, but she couldn't. Anna seemed equally pleased. She jerked her arms up, breaking some of the ice that trapped them. Elsa spread her legs, allowing the tentacle to slide inside her. Her heart beat faster as the tentacle thrust in and out of her. Elsa was feeling a bit light-headed, like she was going to black out. She could feel herself coming to a climax. Elsa arched her back and screamed as loud she could. It was so loud, that it broke the ice off her face. She looked over at Anna, who was writing in pleasure. Soon she screamed too, and the ice on her mouth broke. Elsa massaged her mouth, desperately trying to regain circulation. She dipped her hand below the water and found the tentacle. She stroked it. "Thank you very much."