Keeping Your Feet Warm

My most recent fishing trip lead me to start researching ways to keep my feet warm.  I had to get out of the water and walk around on this last trip because my feet were freezing.  I had on a pair of thick wool socks but they couldn't seem to withstand the chill of the cold water.  The water was maybe 40 degrees.  I was wondering what people in colder conditions do.   I tried googling "keeping feet warm while wading." 

There wasn't an exact answer.  There were more similar answers and from those I think I've devised a plan.   There are a lot of choices out there.  Liners and socks made out of various materials.  There's even electric socks that have a low voltage charge that warms your feet.

From the information I've gathered it seems there are 3 things you want to keep your feet warm. 

1. A roomy boot
2. A nice liner
3. Good socks, preferably wool.

Constriction to blood flow is the enemy.  Keeping circulation is key.  There's a common misconception that the more socks you wear the warmer your feet will be.  This tends to cramp your foot cutting off circulation.  Your feet will get colder and it can create a dangerous situation.  I thought about going with a thicker liner that I'd wear inside my neoprene booties.  Something like this.

The problem is accumulating things around your feet while keeping room.  I could buy another pair of boots and have a winter pair and a summer pair.   That doesn't make much sense to me.  Winter is short around here.  I could look at it like an investment.  I'm really not leaning this way.  The option that seemed made the most sense was to wear a thin liner then wool socks over that.   I will most likely go that route first then if that doesn't work I'll think about more heavy duty options.  There's always those socks that have a pocket that holds foot warmers.