deep thinker said:
Does anybody know of a way to 'stretch' the footpeice of a new pair of open heel fins?
After about 5 min in the water my feet starts to cramp because of the pressure the fins put on the sides of the foot and I was wondering whether there is a way to ease up the 'wearing in' of the fins, like some people do with new hiking boots.
Just in case anybody was wondering the fins are not too small they fit well over the bridge and lenth of the foot its just the width and the next size falls off my feet.
Any advice someone?
Open heeled? Thought spearos normally stuck to full-foot. You might try a shoe tree -- some of the fancier wooden ones spring wide at the front. Sometimes you see special shoe-trees designed to stretch shoes in the classified ads in the back of Sunday newspapers. Or try stuffing them with new paper to apply some pressure inside over a long period -- perhaps warmth would help (is rubber thermoplastic?). Alternatively a cobbler might be able to help. I suppose they probably would stretch a bit with use --
but I have some 30 year old English made fins that I still use from time to time and they
fit pretty much the same as they did 30 years ago.
Face it though
your fins are too small 
-- sounds like that brand does not suit you (since you say the large size also does not fit)
. I would suggest that you take them back & swap them or sell them (locally or on ebay). Have you considered getting a full foot fin (the rear-strap type will always force your foot until it jams something near the front)?
Re. hiking boots, I have some personal experience of walking, climbing, mountain & ski boots ...my conclusion:
make sure they are big enough...either perfect fit or a little big. You can make bigger boots fit using insoles, foot felt & thickers socks (or for diving, neoprene socks, booties or dive boots) but you can't make a smaller boot bigger (actually, a cobbler can get a little extra space out of a leather boot -- but don't count on that). Boots that are too small hurt (sometimes unbearably) and can cause severe cramp. Also
allow for the fact that your feet will swell when warm (& shrink when cold -- perhaps more relevant for fins). Also, for people
with wide feet & stubby toes (e.g. most Brits but not most southern Europeans apparently) --
fit is indicated my how well the width fits not length (there are exceptions: technical climbing shoes/rock slippers) ...with a good width fit you might have an inch of empty space in front of your toes (although less would be better). Gaining or loosing weight can also effect shoe size.
Some brands of footwear fit certain foot shapes better than others (e.g. Nike for narrow feet & New Balance for wide feet). Fin brands are the same (according to other threads) - they tend to suit certain foot shapes ... although there seems to be some disagreement on some brands (I think Miles & another contributor gave conflicting foot shape recommendations for OMER or Picasso!
-- so probably best to try them on).
