All I can remember of this movie is this kid is either at a lake or a pond and what he thinks is a monster turns out to be an old construction digger that was raising in and out of the water due to air bubbles,but he builds this contraption to go under water to find out what it is.

I would greatly appreciate any information anyone could give on this movie.

I think it stars either the kid from ET or the kid from DARYL but I am not sure.

Frog Dreaming A.K.A. The Quest