Exactly. Its xapo custody. 

Back in the day Xapo was buying old military missile silos (I think) that they were using as their off-grid key storage facilities. 

Xapo 

Coinbase purchased Xapo cold storage a few years ago 

Bell_curve

Yes, but internet is not required. You just need enough insider employees who can coordinate their efforts in non-detectable ways. 



freetx

apparently 98% of CB customer funds are stored in offline, geographically distributed cold wallets, which are disconnected from the internet

the liquidity stuff in hot wallets is insured, to a point, so i don't think that would be super catasropihc

bitcoin

Which btc threat vectors concern you most, if any?

stack_harder

apparently 98% of CB customer funds are stored in offline, geographically distributed cold wallets, which are disconnected from the internet 

the liquidity stuff in hot wallets is insured, to a point, so i don't think that would be super catasropihc 