Gold. Nobody buries paper money.

> Common causes of damage are fire, water damage, chemicals, explosives, damage caused by animals (including consumption of the currency) or damage from extended burying of the currency [1].

[1] https://en.wikipedia.org/wiki/Mutilated_currency

Surprised mold isn't on that list. I make sure to add silica gel packets even to my indoor safe these days due to the poor ventilation.

I think mold or fungus could be one of the biggest causes of issue within the "buried money" category

Tell that to Walter White…

"Narcos" might not be fully factual - but I think Colombian drug cartels were burying cash.

When you have their volumes of cash its impossible to launder it.

They don't burry their cash because it makes sense to do so. They do it because it would be impossible to buy that much gold. Or much of anything, really. I wouldn't be surprised if, after expenses, the Treasury is the largest beneficiary of the drug trade through seignorage

if I recall correctly there was a part where they showed some of the cash was ruined.

Actually a lot of people have tried burrying paper money, I guess what you meant is "nobody smart buries paper money".

One of the best choices is PVC plumbing pipe (schedule 40). It's designed to be buried, and with glued end caps, it's also (obviously by design) waterproof. It has to be cut open, and it obviously wouldn't be good for storing huge amounts of stuff.