Gary Grimes portrays Hermie, one of the main characters, a shy and innocent teenager who falls in love with Dorothy while spending his summer on the island.

Jerry Houser

as Oscy

Jerry Houser takes on the role of Oscy, Hermie's best friend who provides comedic relief and moral support throughout their summer adventures.

Oliver Conant

as Benjie

Oliver Conant plays Benjie, another friend of Hermie and Oscy, who joins them in their adolescent escapades on the island.

Katherine Allentuck

as Aggie

Katherine Allentuck portrays Aggie, a local island girl who befriends Hermie and his friends during their memorable summer.

Christopher Norris

as Miriam

Christopher Norris appears as Miriam, another local resident who interacts with Hermie and his friends, adding depth to the island community.

Lou Frizzell

as Druggist

Lou Frizzell plays the Druggist, a character who interacts with the boys during their summer adventures, providing a dose of reality amidst their youthful escapades.

Walter Scott

as Dorothy's Husband (uncredited)

In an uncredited role, Walter Scott plays Dorothy's Husband, whose memory haunts Dorothy and influences her interactions with Hermie.

Maureen Stapleton

as Hermie's Mother (voice) (uncredited)

Although uncredited and only heard as Hermie's Mother's voice, Maureen Stapleton adds emotional depth to the narrative through her poignant portrayal.