“曾经沧海难为水，除却巫山不是云 ”直接英译可以是这样的吧：

Having experienced the magnificence of the ocean，
all other sources of water seem inferior。
Having witnessed the magic mountain clouds，
all other clouds are of no significance。

如果意译，我简洁地译成：
Having seen you the most beautiful girl，
I know I will never love anyone but you.

诗不可译。 ....