Sony sells decks and recorders for their high-capacity "Professional Disc" that can hold up to 128GB per disk. And then there is their cartridge to compete with LTO, the ODA Gen 3 that holds, IIRC, 11 discs with a total of 5.5 TB per cartridge. A bit less than LTO-7 (and half as much as LTO-8), but I don't think LTO tapes can survive being boiled in water.