Crunchy is the culprit behind Motoshondu.
Motoshondu is a sea serpent, actually a robot created by Crunchy Granville to protect underwater wildlife.
History
What's New, Scooby-Doo?
Season one
Granville had a second way to create Motoshondu - he mounted a large flat-screen TV to the bottom of his glass-bottom boat and projected a CGI image of the sea monster attacking, which frightened tourists while giving him a solid alibi. This second method backfired when the gang panicked and steered his boat onto rocks. (She Sees Sea Monsters by the Seashore)