unsinkable

1. (chiefly of ships) That cannot be sunk.Examples: "Any true Grecophile will understand when I say that the unsinkable condom and the smell of shit which precede the moment of illumination make it more exciting when it happens."; "It was the kind of place with a neon martini glass for a name and an unsinkable turd floating in the toilet."; "That was the connection, the hook, the key, that was the thought that had been bobbing around like an unsinkable turd in the toilet of my subconscious all night."Synonyms: sinkproof

2. (figurative) That cannot be overcome or defeated.Examples: "unsinkable optimism"figuratively