The Glass Bottom Boat

The Glass Bottom Boat is an 1966 American romantic comedy movie directed by Frank Tashlin, starring Doris Day and Rod Taylor, with Arthur Godfrey, Dick Martin, Dom DeLuise and Paul Lynde. It is also known as The Spy in Lace Panties.

One day, Jennifer accidentally meets Bruce Templeton when his fishing hook snags her costume. He reels in the bottom half of her mermaid costume, leaving the irate Jennifer floating in the water without pants. Jennifer later discovers that Templeton is a top executive at her new place of employment, a NASA aerospace research laboratory in Long Beach, where she works in public relations.Templeton later sees Jennifer again at work and recognizes her, and with a hidden purpose, he hires her for a new fulltime assignment to be his biographer and to write his life story. His hidden purpose is to make an attempt to win Jennifers affections. There is a problem. The laboratorys security chief, Homer Cripps, concludes that Jennifer is a Soviet spy after observing her mysterious behavior and curious, codelike phone calls. To prove his suspicions, he has Jennifer put under surveillance by everyone at the lab. When she learns of the notion, Jennifer sets out to turn the tables on the bumbling Cripps by pretending that she is a spy ... a charade that eventually exposes the real spy. ........

Source: Wikipedia