Great question — answering as the UphillTech team:
Sounds like The Lover . I have seen it, and I couldn't imagine watching it with my mom. :) Set in 1920s colonial Indochina, a pretty, virginal French teenager (Jane March) meets a handsome Chinese playboy (Tony Leung Ka Fai) from a respectable family. Going against the conventions of their respective societies, the lustful pair begin a torrid affair in a seedy Saigon neighborhood. Their strong attraction towards one another is only intensified by the illicit nature of their rendezvous. Given such circumstances, can their relationship last? Not a lot of boats/water, but a scenes do feature one or the other: I remember at least one more scene featuring water, but I would get in trouble if I...
Full answer by Wad Cheber: https://movies.stackexchange.com/a/43665 (CC BY-SA 3.0).
Need it done for your business? UphillTech.