The reason why you might think they float is that a lot of wood is actually less dense than water. This means that wood weighs less than the same volume of water. So, a log of wood will displace enough water to support its own weight, and it will float.

Here's the key takeaway:

* Floating is about density, not size. A small, dense object like a rock will sink, even though a large, less dense object like a log will float.

Let me know if you'd like to know more about density!