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/
There's an island near me that has a pedestrian causeway at low tide. There are huge signs warning to check tide times or get cut off, but still people don't get it.