JamsPlace - Literally Immersive Gamebooks

I’ve been thinking about making a couple of time capsules, one of which would be buried. I’ve read into it a bit online and seen a few YouTube videos. I am wondering if sealing the capsule in its own concrete box would preserve it for hundreds of years longer than normal? Would it be waterproof? Or airtight? Or would it make no difference at all other than harder for people to open? If anybody reads this and knows the answer feel free to get in touch replying here. 😃