Another humidity damaged tag. Board water proof coating?See a view of the board

I put a ruuvi in the sand in the swamp to measure the sand temperature related to turtle egg research. I got back 3 weeks later to find that the ruuvi had halted. It appears that an animal had bitten a tiny hole in the gortex. Between that and the normal;y high humidity it looks like corrosion had done the deed. See attached.

Thisn seems to be a common point of failure.

How difficult would it be to seal the board (except the humidity sensor) to prevent this?

See a view of the board