Where is the sub woofer located?

This is part of my 2010 Prius' original invoice info:

8 speakers. The bass is enough to numb your skin from your hair vibrating.

Isn't there a subwoofer installed? If so, where is it?

Trying to remember though... if there is
1 each front door,
2 in dash,
2 in each back

That is 8. The stock stereo is pretty killer, but I am guessing there is no subwoofer?

 

well.... Wow... Amazing base for no subs. Just the right ammount.