Faerie Tale Theatre (1982)

Season 6: Episode 2

Pam Dawber makes a deal with a sea witch after rescuing a human from drowning -- she wants to become human. The witch agrees to give her legs, but the prince must fall in love with her or she is doomed to be sea foam forever on the sea. The Witch also takes away her voice and warns her that every step she takes will feel like she is walking on knives. Even with all odds against her, the little mermaid follows her heart, no matter where it may lead!