That will probably work about as well as the proposal to put a data center on Sealand [1]. Or Cryptoland. Or Satoshi Island. Or Blueseed.[2]
Or the Space Kingdom of Asgardia, which launched a successful satellite with some data storage in 2017.[3] That lasted until 2022, when the satellite re-entered.
[1] https://en.wikipedia.org/wiki/Principality_of_Sealand
There are a lot of countries with navies that could just happen to decide to conduct a live fire training exercise in the general area as your ocean facility and just happen to have an accident that takes you out, with enough plausible deniability that they probably would not get in any serious trouble over it.
There are a much fewer number of countries that could take out a lunar facility and I don't think any could do it in a way that has any plausible deniability.