A calamity, misfortune, or disaster — an unlucky or harmful event such as a disaster or accident; can also refer to personal misfortune.
台風で家が壊れるとは本当に災難だった。
It was truly a calamity that the typhoon destroyed the house.
忙しい時に限って怪我をするとは災難だね。
It's unfortunate to get injured just when you're busy.
あの店を見つけられなかったのは小さな災難にすぎない。
Not being able to find that shop was just a minor misfortune.