Observations?

I'm looking for some inspiration guys... 
Has anybody of you made an interesting observation or heard of an interesting observation?
For example, the observation:
You swim faster in shallow water
I need to write an essay in physics and I think I am going to write it on an observation as such, investigating it.
If anybody has any, it would be appreciated!
PS It is true, you do swim faster in shallow water.

Has anybody of you made an interesting observation or heard of an interesting observation?
For example, the observation:
You swim faster in shallow water
I need to write an essay in physics and I think I am going to write it on an observation as such, investigating it.
If anybody has any, it would be appreciated!

PS It is true, you do swim faster in shallow water.
