Tell Me What You Know About Merfolk?

I don't hate merfolk, but there's a good possibility you could die if you ever do encounter them. They sing when they know a human is coming near, the singing buts you into an almost hypnotic trance, and they drag you under the water to be with them, but there's a problem, we can't breath underwater. As far as them speaking underwater, it's got to be the same way dolphins or whales speak, you can't speak like we do under water.