0.5mm dive socks from a dive shop? Would have to fit and remove them at the water's edge as they're not designed to walk over sand/rocks.
etc.
1mm and 2mm thicknesses are also available.
Hope this helps.
ahhh the age old question of booties or no booties. It all comes down to how much you're willing to suffer for the feel of the board. Only you can determine if the juice is worth the squeeze.
DC
I've got some cuts on the bottom of my feet so been wearing reef/aqua shoes. Works really well, at least on a strapless board.
