#3135: Sea Level

XKCD comic, described below.
Transcript

[Single frame, with Megan and Cueball standing at a coastline with grass, with water and waves visible. They are looking at the ocean and are standing together.]

Cueball: Hey, where's that big island we were looking at this morning?

Megan: Oh, it's underwater. The ocean's depth here goes up and down by like ten feet every day.

Cueball: What?

Megan: It's because the planet has a big moon orbiting near the surface. It causes weird gravity effects.

Cueball: What???

[Caption below the frame:]

People here are used to them, but tides are one of the weirdest and most sci-fi elements of life on Earth.


(Sourced from explainxkcd.com)

Title text:They're up there with coral islands, lightning, and caterpillars turning into butterflies.


ExplainOriginal