Whale watching is a thing people do in order to experience a sense of personal relationship with whales.
Whales are big, ponderous, improbable things that live in the sea. People are just improbable.
Whale watching usually requires that the watchers ride in boats a good deal farther from land than they anticipated. Consequently many whale watchers spend a good deal more time thinking about their stomachs, drowning, and taking up bird watching than they do seriously looking for whales.
As a result, most of them relegate the actual business of looking for whales to a professional guide, whose job it is to shout encouraging things like 'There's a fin... could be a minke!' at well-timed intervals.
There is, of course, no guarantee that there will be any whales, or that the average person will be able to spot them if there are. Usually though, a competent guide will find at least one.
That's the really disappointing part. Whales are so perfectly suited to the sea that many people find it difficult to see them even when they have been pointed out.
Many people are also surprised by how perfectly their enormous forms are accommodated by the sea. A whale in the sea is visually far less dramatic than a whale on a hoist at the garage. In the sea, whales look like big, shiny slugs. They are big, strange animals in a perplexingly alien environment. It is annoying to find oneself staring rapturously at the wrong bit of sea.
Occasionally, whales do spectacular things like jumping in the air or waving with their tails. This is generally considered to make the whole endeavour worthwhile. But many people have ambiguous feelings about this; and some decide outright that next time they will go to Marineland1.
[Editor's note: Having swum with a minke whale, I can safely say that whale watching, for me at least, was wholly worthwhile... so there.]