Discovered a few weeks ago when we had a river swim….
I took an isothermal bottle full of boiling water, my daughters mini hot water bottle and two haramakis – one cotton for next to the skin and an ultra-warm angora core-warmer. Once out of the water and dressed (and while my fingers still worked) I filled the hot water bottle with the boiling water and popped the hot water bottle in my roo pouch of haramakis. Combined with my robe I built up a nice warm core radiating heat. Added tea and amazing marmalade cakes and I was a very happy post-swim seabird! Been doing it ever since to beat the after-drop….