I can vouch for the dolphins and whales to being intelligent. When we lived near Big Sur in CA, my mom used to take me and my siblings to the beach. Sometimes really early in the morning, we'd go when no one was around and she'd play her pan pipes. Next thing a pod would show up and we'd swim with them! They can in fairly close to the shore, they didn't have to come over but they did. And they seemed to like the sound of the pan pipes too.
When we visited some family in Haiti, I was a lot older and could join my mom & older sister when they went snorkling. There were some dolphins there that came around and watched us, they seemed to like my mom. She had this little harp like thing that she would play under the water. They really liked it, but I couldn't hear a thing.
We even had a small whale show up once and it really was a bit scary cause he looked big as a bus to me! My mom told me later he wasn't all that big. So I have some great memories of living by the oceans.
Too bad things have changed so much over the years. It's sad how so many parts of the ocean are dying, or sick due to pollution and climate changes.
Me? I believe the guy!