Guild Wars 2

It doesn’t appear that the #6 rune works underwater but shows back up when on land.

Do you have a Superior Rune of the Krait in your Aqua Breather as well?

Doh!
I don’t actually. I’ll remedy that now.
Thanks for clarifying.

Hehe I made this mistake too (not with this rune though). While underwater your helmet is “replaced” by your aqua breather, so both need to have that rune if you want the complete rune stack.