book cover is damaged.its an old book.


"After an earthquake strikes while Robin Kane is at school her science teacher, Mr. Smith, tells the class how earthquakes can disrupt the depth of the ocean and cause elusive and mysterious sea creatures to appear. School is let out early and Robin, her brother Kevin, her best friend Mindy, and Mindy's brother Mike all head to the beach. There they run into an excited Mr. Smith who informs them he has just sighted a strange, Loch Ness type creature in the water. Mr. Smiths story spreads fast and although Robin and her friends believe him the rest of the town is skeptical, especially after a second appearance of the creature turns out to be a dummy constructed with items from Mr. Smiths office.
Robin is eager to prove Mr. Smith correct and takes up watching for the creature whenever she can. When Robin and Mindy's families arrange a joint outing to Rancho Lucia, a ranch owned by Mindy's father, Robin takes Mindy and her younger sister, Amy, on a horse trek to a cliff overlooking the bay where they can look for the creature. Robin and Mindy leave Amy with the horses while they go take up a watch and are ecstatic when they both see the sea creature. Soon after they hear Amy scream and as they run to her aid they fall through the ground into an underground cavern."