The Secret of Roan Inish is a 1994 Irish/American indie film directed by John Sayles about a little girl trying to get her brother back from seals. It is apparently based on the novel Secret of the Ron Mor Skerry by Rosalie K. Fry.
Fiona is a girl sent to live with her grandparents on the Irish coast due to her mother's death and her own health issues. While there, she's told the story of her little brother, Jamie, who was taken by the sea in infancy. Their family had lived on the island Roan Inish, which is visible from the shore of their current village, but during the move over Jamie's bassinet fell into the ocean and was carried away like a little boat. Fiona also learns of the selkie legend from one of her cousins, and how their family has a selkie-woman ancestor whose selkie blood occasionally pops up in their relatives, giving them a strong desire to go to the sea.
When Fiona begins to see a little boy in a tiny boat out among the waves, she realizes that her brother is alive and has been cared for by the seals on Roan Inish. She and her cousin, Eamon, come to the conclusion that they must convince their grandparents to move back into the dilapidated Roan Inish home so the seals can give Jaime back. Meanwhile, her grandparents' landlord is selling their current home, giving the kids a limited timeframe to fix the Roan Inish house.
The film is a charming, magical realism kind of fairy tale, and is pretty timeless in a weird, rural way that strongly reminds me of the 1993 Secret Garden.
Trailer is here.