Another thing some of us use, it looking for the tell-tale bubbles in a circle, w/diving birds in the area. This will usually mean Whales are bubble net feeding. The birds are merely there to catch a lucky fish or two that escapes!
I tell passengers on my boat, look at the horizon, and now, let your eyes drift slightly below the horizon. Look for a puff of mist.... that may be a whale, blowing air to clear water from their breathing hole.
My kids, when they were much younger, called this looking for the 'sprout'