It can't be a stupid question, you are smart enough to ask, rather than make up something like everyone else.
Clarity and coral formations...... You can't see your hand in front of your face off either coast. The waters of the Caribbean are so pure sunlight penetrates nearly 100 feet in places. Coral formations lose color definition without lots of light, that's why underwater photographers have to use flash. We learned to dive living in the Caribbean. Spoiled us for anywhere else. Same thing in the Pacific islands. If you live there you never get tired of it. Never mind why the waters off our coasts are so murky.
More than you ever wanted to know.