From about June through September every year, the humpback whales come up from the Antarctic toward the equator. They don't eat during this time. Instead, they calf and mate. In Puerto Lopez, you can take a boat out whale watching for about $15 or $20 per person, depending on your tour guide and the type of boat you take.
The guides will warn you that it is at your own risk. The whales don't know to be careful where they breech, and there may be some under the boat at any time.
When the driver sees the first spout in the distance, he heads toward it. The whales will breech, swim, and play with boats surrounding them. They don't seem to notice or care that the boats are there, so long as nobody tries to mess with them, and nobody does. It's an awesome experience. I would recommend it to anyone.