Don't travel with out some of these...

Maybe if you are going to Antartica or Alaska... depends on your tolerance to cold.  I personally find a pair of these is perfect for a second set of shoes and can even be hung off your backpack.  p.s.  if you watch one of the slide shows below I am modelling mine.  LOL!

I've worn out more pairs than I can count.  They work in water and can be your camp slippers, with socks if needed.
Just thought I'd throw it out there since summer is coming!  Happy Travels... soon, soon...  YAY!