Meaning:

Literally translated as “The little boat has already carried me past thousands of hilltops,” this is a widely recognized verse from Tang Dynasty (618-907) poet Li Bai. Li used this line, found within his four-line poem “Departing From Baidi City at Dawn,” to convey his overwhelming joy upon discovering his exemption from exile to the contemporary Guizhou Province, allowing him to return to his friend in Hubei. In modern times, young Chinese individuals use this phrase akin to the English proverb “water under the bridge,” signifying past issues that no longer trouble them as they're unchangeable. This expression frequently surfaces in discussions relating to past relationships or former partners.

Example:

A: 你弟弟还喜欢他高中学校的校花吗？

Nǐ dìdi huán xǐhuan tā gāozhōng xuéxiào de xiàohuā ma？

Do you think your younger brother still holds a flame for his high school crush?

B: 轻舟已过万重山。他大二找了个同校女朋友，一直很稳定。

Qīngzhōu yǐguò wànchóng shān。 Tā dàèr zhǎo le ge tóngxiào nǚpéngyou， yīzhí hěn wěndìng。

That’s water under the bridge. He’s been with a young woman from his college since his sophomore year.