Such that it cannot be sunk. / (figuratively) Such that it cannot be overcome or defeated.

Of a ship: that cannot be sunk. / (figuratively) That cannot be overcome or defeated. / A piece of faeces that floats.

That does not sink.

The quality of being unsinkable.

The quality of being unsinkable.

plural of unsinkable rubber duck

A belief in a supernatural or paranormal phenomenon that people continue to hold, in spite of it being debunked.