drop in the bucket; drop in the ocean; a tiny fraction of the whole
Idiomatic expression emphasizing extreme insignificance compared to a vast whole. Often used in formal or literary contexts.
His donation is just a drop in the bucket, but it still helps.
この問題に比べれば、私の悩みなど滄海の一粟だ。
Compared to this problem, my worries are just a drop in the ocean.
Similar meaning (a single hair from nine oxen), also expressing insignificance, but less common than 滄海の一粟.
Standard kanji form; 滄海 means 'vast ocean' and 一粟 'one grain of millet'.
Variant using 蒼 (blue/deep) instead of 滄 (vast); both are used in this idiom.
From Chinese classical literature; the phrase likens a single grain of millet to the vastness of the ocean, emphasizing extreme smallness.