The endless sea of suffering; refers to the Buddhist concept that human existence is a cycle of pain without end, or more generally to any environment of extreme hardship or misery. Usually followed by the phrase [[回头是岸|回頭是岸|hui2 tou2 shi4 an4]].

(idiom) the sea of bitterness is vast; used to describe a life full of endless suffering and hardship

To escape from an abyss of suffering or a wretched situation; to be delivered from a life of misery (often used in a Buddhist context to refer to the cycle of reincarnation, but commonly used for any dire circumstance)

(idiom) The sea of bitterness has no bounds, turn your head to see the shore. Originally a Buddhist concept meaning that enlightenment allows one to escape the abyss of worldly suffering, it is now used to urge people to repent and turn away from their wrongdoings to find a way out.