Submerged: Discovery

A family that consisted of father, mother, and child went on a vacation boarded a Cruise Ship. They spent their time having fun in the ship until a storm came so they needed to go into their cabin. It was already morning when the storm went away. On a certain night the child, after sneaking out from his parents found a weird thing at the deck, it was a claw of some kind of animal but the kid being an animal enthusiast never saw anything about it. He was examining it when suddenly the floor started shaking violently, the shaking lasted for a while before the shaking suddenly stopped. After getting on his feet it saw out in the sea was....a spine, a spine like the one in one of the dinosaurs but it isn't just that......, it was gigantic. Like.... the size of it could reach half the height of the cruise he's boarding on right now, but after staring at it for a few seconds, it suddenly started becoming small?, No! It was submerging! The kid looked for his camera wanting to take a picture of it but couldn't as he left his camera at his cabin. So he went to take his camera but when he came back... it was gone.. in the time he went to take his camera, the spine or whatever it was, was gone. He looked for it for a while but it's nowhere to be seen.. After a few moments, he heard his mom yelling looking for him so he left the place after taking a look at the deep blue ocean one last time.
The thing he saw left the kid with a lot of questions. Was the thing he saw real? Was it a hallucination? If it was real, what was it? No one can answer his question.

Beneath the calm surface of the ocean, thousands of meters deep, a large reptilian creature opens its slitted yellow eyes...