Riddle

In we go, out we go. All around and in a row. Always, always steady flow. When we'll stop, you'll never know. In we go, out we go.

Choose an answer

A.A river
B.A pendulum
C.A heartbeat
D.The tides
Hint: It's a 2-word phrase with 8 letters, starting with "T".

Answer

The tides

Why this is the answer

Tides rise (in) and fall (out) in a steady, endless rhythm around the coastline, and no one can say exactly when that cycle will ever stop.

This riddle is filed under Hard/Difficult Riddles and rated Medium.