South Korea’s Han River (한강, Hangang) is much more than a river—it is one of Seoul’s most recognizable landmarks. But in March 2026, it unexpectedly became the center of an online controversy involving a popular finance app and Korean internet culture.

What happened?

Korean fintech company Toss introduced a small feature that displayed the current water temperature of the Han River. The feature was originally intended for people enjoying water sports, fishing, and other outdoor activities. However, many users immediately associated it with a well-known piece of Korean stock market slang.