A picture from the Hopewell Rocks, in Canada’s Bay of Fundy

The Bay of Fundy has arguably the highest tides in the world, about 17 meters — the result of an odd resonance in the bay (a wave will travel from the mouth of the bay to the inner shore and back again in about the same time as the spacing between high tides). One of the offshoots of these tides is that a lot of ground gets uncovered at low tide.

Here, you see my daughter (just turned 7 when this picture was taken) standing under the middle of “Lovers Arch.” Come back in 12 hours, and only the green top of the arch will still be above water.