Observing sea life is a ver interesting pastime. Most of the creatures that you are trying to see don't make their way up the surface that often. There's also some danger of harming they very wildlife that you want to see, but a great captain should be able to keep both you and the sea life safe.
These people, however, witnessed a once in a lifetime opportunity that they won't soon forget. They wanted to go whale watching, which is something where you usually go out for hours and occasionally see a couple of whales in the distance. This is something way above and beyond of that, however.