noun
tiger's den; lion's den; very dangerous place
Figurative expression for an extremely dangerous place or situation. Often used in the proverb 虎穴に入らずんば虎子を得ず (Nothing ventured, nothing gained).
敵の本拠地に乗り込むのはまさに虎穴に入るようなものだ。
Going into the enemy's stronghold is like entering a tiger's den.
彼は虎穴に飛び込む覚悟で、危険な任務を引き受けた。
He took on the dangerous mission with the resolve to jump into the lion's den.