I had a dream just now, where my room was bigger, much bigger, and full of water. Dim nightlight shot in through the window from unknown sources, and I was floating, but not alone. A blue whale was there, wishing me a late happy birthday. It swam around me, and I could touch it.
Goddamn. For the longest time, I had known how big they were: length, weight, size of organs and everything, but never really realized it up close like this. I was afraid she'd just happen to open her mouth, and suck me in along with all that water.
There's power in so much immensity. She'd kill me without meaning to. But she didn't. She just rubbed against me and wrapped her fins around me - gently, so that I could escape and swim out my door for air and come back in again. It was one of those dreams you'd never want to wake up from.

You know something else about whales? They're the loudest animals on the planet. The low-frequency-whistle call of the blue whale can reach levels of over 180 decibels (a good deal more than a jetplane), and during the right underwater conditions, these sounds can travel for thousands of miles.
Of course, the oceans are vast and the speed of sound is limited, so over distances like that, it may well be an hour or two before a message finds a recipient and an eventual reply is sent back.
Now, this is harder to prove, but I personally think this is why whales communicate the way they do, serenading for several minutes at a time, and then starting over and repeating the exact same message.
It's what they have to do. When you don't know if anyone is listening, or how long it'll be before you get some kind of reply, you broadcast a soliloquy; you communicate with long messages in order to make up for the time-lag between sending and receiving, and you send those messages again and again, to make up for the risk that they never reach their intended targets. This is the means of communication we would choose to send messages to the stars, and it is what we listen for in search of extraterrestrial civilizations: repetition.
When I think about it, they are like the echoes of whales, as simple as they are beautiful.