Legend of the Mer — Sheri L. Swift

Lana Prentis is 17 years old and has some unusual physical challenges: she has white hair, silver eyes, milky-white skin and webbed fingers and toes.
   She lives on Safe Harbor Island off the Coast of North Carolina. Her father (Cole Prentis) is the lighthouse keeper and also the keeper of many secrets.
   He told Lana her mother drowned when Lana was only three years old, and he never allows her in the water.
   When Lana's P.E. Teacher (Miss Rose Perry) secretly gives Lana swimming lessons, it sets off a chain of events that leads Lana to discover the truth about herself and her mother.
   Lana learns her true life's purpose, that her heritage is as rich and deep as the sea - and her future lies beneath it.