do you think sea monsters were real?

Depends on your definition of a monster. To me, those big nasties from eons ago that have left fossils scattered about were monsters. Sharks, orcas, barracudas and the such are modern sea monsters. That is coming from someone with a fear of the ocean and other deep bodies of water, so my definition may not match yours

When you look at the almost infinite forms of life in the oceans it's not hard to see why people called them monsters.

Dinosaurs were, why wouldn’t they be?