ボートはたちまち沈んだ。

ぼーとはたちまち沈んだ。

The boat sank in a flash.

ボートはたちまち沈(しず)んだ。

Bo-to wa tachimachi shizunda.

ボード (ボード)

board

は (は)

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

忽ち (たちまち)

at once; in a moment; suddenly; all at once; quickly; promptly; immediately

沈む (しずむ)

to sink; to go under; to submerge; to go down (e.g. sun); to set; to descend; to feel depressed

Readings: チン、ジン、しず.む、しず.める

Meanings: sink, be submerged, subside, be depressed, aloes