Off site Secure Tape storage [closed]
Solution 1:
I agree. Iron Mountain is everyone's industry standard. They are reasonably "cheap," feature "possession tracking" (everyone that handles them signs off on the handling), and operate nationally across the U.S.
Other methods would include storing them in a trusty employee's (like COO for instance) house in a "fireproof" safe that's specifically designed not to allow it's contents to reach the wicking point of whatever media you use.
Either way your tapes should already be encrypted; hopefully with at least a 256 bit AES key, where the passphrase's entropy is quite high.