The Bay of Fundy, on the inland side of Nova Scotia, has some of the highest tidal fluctuations in the world. Here’s an example from Halls Harbor, near the end of the bay.

You probably already know this, but spring tides don’t happen just in Spring. They occur about every two weeks, on the full and new moons, when the sun, earth and moon roughly align. The sun and moon’s combined gravitational forces make the tides higher than normal. When the moon is perpendicular to the alignment of the sun and the earth, the forces don’t line up and the tides are lower than normal. Those are called neap tides. They also happen every two weeks, between the new and full moons.

Since the moon doesn’t move that much in a day and the earth spins once in 24 hours, there are roughly two high tides and two low tides per day. Picture the earth spinning inside an ellipsoid bubble of water. The two longer ends of the ellipse are the high tides, the two narrower bits in the middle are the low tides.

Curious where all of the worlds highest tides happen? Check out this map.