Why does air travel faster in water?

Answer 1

As opposed to travelling in what?

But if you mean sound then its because sound is - technically speaking - a vibration of the molecules. It is slower in air because the molecules are farther away from each other, and thus the molecules take much longer to interact.

In water, the molecules are closer together, and therefore pass on the vibration quicker.

This also relates to why water takes sound much farther as opposed to air. :)