The Glass Bottom Boat

A suave inventor and entrepreneur who leads the GISMO project. He is confident, quick-witted, and tends to trust his instincts, sometimes underestimating suspicion around Jennifer. His drive to see GISMO succeed propels the plot and creates friction with those who doubt him.

Bruce's public-relations ally who is recruited to write his biography. Witty, resourceful, and emotionally invested, she becomes entangled in the espionage web and navigates distrust with humor and charm. Her clever handling of suspicion drives much of the film's romantic-comedic tension.

Operator of the glass-bottom boat business; affable and protective, he provides a warm anchor in the seaside setting. He befriends Bruce and Jennifer, contributing to the movie's light, friendly humor. His island enterprise helps stage many of the film's touristy, blue-water scenes.

Electronics technician who handles the GISMO project on-site; curious and ambitious, he inadvertently helps expose security flaws. He photographs the cryptic note and passes images to his handler, blurring lines between ally and spy. His actions propel the plot toward the party and confrontation.

CIA agent tasked with securing the GISMO project; sly, capable, and willing to bend rules to protect the secret. He plays a central role in the spy-versus-spy intrigue and ultimately reveals the real motive behind the plot. His presence adds tension to the party and chase sequences.

Security guard who is suspicious of Jennifer and quietly observant of all the moving pieces. His stool-pigeon-like surveillance adds a layer of comic misdirection. He becomes a casualty of misunderstandings as the truth emerges.

PR executive who takes part in the party-plot dynamics and helps keep the GISMO project moving from a public-relations perspective. He contributes to the film's breezy, social set-up and the interplay between appearances and reality. His presence showcases corporate-side espionage tensions.

Air Force General overseeing GISMO's security; vigilant about leaks and ready to intervene. He embodies the government angle and the pressure to protect a potentially world-changing discovery. His involvement amplifies the film's Cold War edge within its comedic frame.

Neighbor who gets pulled into the caper and ultimately helps stop the villain with a lamp. She provides comic relief and a practical counterpoint to the main espionage drama. Her quick action helps avert the theft of the formula.

Mabel's neighbor/husband, a supporting presence in the seaside community. He adds to the film's ensemble vibe and the background humor. While not central to the plot, his presence helps color the Catalina setting.