Title text:
They're up there with coral islands, lightning, and caterpillars turning into butterflies.
Transcript:
Transcript will show once it’s been added to explainxkcd.com
Source: https://xkcd.com/3135/
Come to the beach here in Bordeaux (well, on the coast) and see tourists set up their stuff at low ebb but forgetting they have to watch out for the flood.