Encase them in amber, then pile a mountain of silica gel on top, then put in an air-conditioned vault, underground. Fill in the access tunnel with soil and plant a tree over that. Build a tree house in the tree in a few decades. Put a machine gun turret in the tree house. Get the property declared a historical landmark. Remember, it's not only nature that is the enemy of your data.
Above all else, never let sun or light or air or humans (animals have no interest in DVDs, except monkeys, keep monkeys away) get to them. Never check on them, never access them. Do not use a GPS locator emanating a beacon. Do not lead anyone to your stash. They must stay there forever.
If I didn't already have some context behind your several related posts, I would have just told you to rip the ISO images to a flash drive, then once every decade or two, copy that to a new flash drive. Flash memory is non-volatile but will lose data after a few years, or even less if it is nearer its write cycle limit which it won't be if it is a new flash drive used only once to write the data to.
THAT, you might have a legitimate reason to pack with silica gel, in an opaque waterproof container and store in a temperature controlled room, if everything around you is corroding, while most people could just keep one copy in a drawer and another in a safety deposit box at the bank.
If you want to spend more money for the more time tested strategy, rip the ISOs to magnetic tape then store as above in a vault, humidity and temperature and light controlled. The tape drive interface and driver/host-OS compatibility should be considered, to have a host capable of reading it decades from now, at which point you may find your tape drive has rotten rollers, gummed up grease, and won't work unless maintained over time. IMO, USB flash drives are more likely to be supported without that hassle.