My one wish

Merlea was just a typical teen age girl. She only had a couple friends but non were really close to her. Her only close friend as was lilli Haskell. The too girls like to not only be outdoors but to be in the water. The girls are both foster kids. Merlea knows nothing of her real parents , while Lillis parents are trying to get in touch with her. The too Girls where swimming in the east coast practicing for swim tryouts when they find a mysterious cave. Will bad thing happen if they go inside? Or will they avoid the trouble of never getting to compete in swimming?