Are Mermaid Man and Barnacle Boy really the Navy’s dark, forgotten secret? Join Dan Casey as he *dives* into the theory. 10.24.2019. Created with Sketch. Created with Sketch. Created ...

Fans have had their theory about the cartoon’s world and how SpongeBob’s two favorite heroes came to be. Mermaid Man and Barnacle Boy made their debut in a self-titled episode in 1999.

Nickelodeon honors the late Ernest Borgnine with a two-hour SpongeBob SquarePants marathon featuring the actor as Mermaid Man, from 2:00 p.m. — 4: ... Borgnine–“Mermaid Man and Barnacle Boy ...