On 5 Mar, 10:30, Huge wrote:

From my diving days, the standard ways of preventing your mask from
steaming up were either to gob in it or smear it with soap or washing
up liquid.

Snot works better (clear, not aspirated), and you can even do this by
wiping a slug on the inside of your facemask.

Bristol's Department of Mucus Studies is just up the road, and you can
learn all sorts of stuff from them. From people obsessed with fondling
slugs, admittedly. Say hello, but I wouldn't want to shake hands.