People find dolphins charming. This is not news. It's rather odd, though, as in real life dolphins can be murderous vagabonds and brutal sadists: perpetrators of sexual violence who also enjoy torturing their innocent victims for their own personal satisfaction. They may seem like they are friendly and playful, almost laughing along with you as you watch their acrobatic leaps, but look at the eyes: the eyes are studious and mean; the eyes contain depths of contempt; the eyes never laugh. To look into the eyes of a dolphin is to look into the cold, calculating eyes of a sea-dwelling sociopath. They are the eyes of a predator.
But small girls think they're cute, so "swimming with dolphins" ends up on most people's bucket list.
In fantasy too, people have more or less universally fallen for the myth that dolphins are on the side of the angels. Friendly allies, or even super-intelligent founders of underwater civilisations. This reached its apogee in the 2nd edition AD&D Monstrous Manual, in which dolphins are Lawful Good, have an intelligence of 11-12 (bear in mind the human average is 9-12), and are described as "benign" and "inherently peaceful". One suspects the AD&D Monstrous Manual would not have been written that way if it had been created by mackerel.
We have a failure of imagination when it comes to cute or intelligent animals. We have a natural tendency to impute them with emotions and ideas that are not their own. Animal lovers (I count myself one) are especially guilty of this. It's odd that the more time one spends thinking about and looking at animals, the more one tends to develop this blind spot about them. It often does them a disservice: it infantilises them. It reduces their complex and fundamentally alien nature.
I don't have a great deal of time for Wittgenstein, but he was on to something with his famous remark about the lion. If a dolphin could talk we could not understand him. Or, if we could translate all those clicks and hisses and supersonic squeaks, we could still not understand them. Wittgenstein meant that to understand language you needed to understand the social context; like a lot of philosophers he wasn't thinking very clearly - the problem with an animal isn't the different social context so much as it's the different biological one. A dolphin brain is not a human one. Their thoughts are not of a human nature, and in fact the act of trying to make them understandable to humans necessarily reduces them and transforms them into something they are not. It denies the richness of an individual of another species' lived experience and the possibility of true difference.
That's not to say that it isn't fun to try, though. What thoughts would you think if you were an intelligent, efficient predator who grew up in the sea and had never gone on land and indeed hated it and was terrified by it? What if you had no idea where the next meal was coming from and lived in a perpetual state of searching with your extended family for sustenance? What if you were one of the great swimmers, an ocean-going nomad, who was still tied to the air as if there was an invisible leash constantly dragging you back to the surface? As if you could never be truly free? (Or to spin that last thought on its head: imagine if every 10 minutes you had to go and dip your head in the ocean in order to stay alive.) What if every so often big brutish cold hard objects, which you had no words for, and crawling with mewling, jabbering creatures, churned the ocean surface above you? What if sometimes those big objects were dragging great webs between them which threatened to tangle everything in the sea up inside them?
Now think of a hawk, or an ant, or a pig, or an ape, or a crocodile. What would you think if you were one?