Gold  Key © December 1970, Hanna-Barbera Scooby Doo... Where Are You! #4.  The story is "The Ghostly Sea Diver". 

With works by: Script: Cecil Beard, Alpine Harper   Pencils: Jack Manning    Inks:  Jack Manning

This book appears in (f/vf 73) with the expected nics, tics, wear and tear. Thanks for looking.     3635-xxxx-73