Pam Wright, age 10, of Peterboro, Ontario, Canada, for her question:

Where are the world's largest tides?

Everyday, high tides and low tides chase each other around the globe. The rising and falling water is not very noticeable far out at sea. But we certainly notice when the tidal water heaves up and down along the shores. Experts on tides say that the world tides jog in global patterns. Around Tahiti in the mid Pacific the difference between high and low water is merely a foot. Cook Inlet in Alaska is in a different tidal zone. Here, and in about five other zones, the tidal water rises and falls 30 feet or more.

The Bay of Fundy sweeps between Nova Scotia and the coastline of New Brunswick. Here, everything is just right to create the highest tides in the world. It is one of the extra strong tidal zones and the shorelines are shaped to force the heaving water into a funnel. At low tide, the water is pulled back out of the bay. When the tide turns, a wall of water four feet high comes roaring down the funnel. If this were drinking water, there would be enough to supply everybody in North America for two months. In the Bay of Fundy, the world's biggest tides lift and lower the water level at least 40 feet twice every calendar day.