Danny Dunn on the Ocean Floor is the fifth novel in the Danny Dunn series of juvenile science fiction/adventure books written by Raymond Abrashkin and Jay Williams.

Another accident in Professor Bulfinch's laboratory, instigated by Danny, results in the creation of a transparent, resilient material.

The material proves useful in creating a bathysphere, and Professor Bulfinch, along with his friend Dr. Grimes, Danny, Joe, and Irene, descend into the Pacific Ocean on an experimental voyage.

On their journey, the submarine is examined by a giant squid and attacked by a large shark.

Floyd C. Gale of Galaxy Science Fiction rated the book 4.5 stars out of five for those aged eight to twelve.