In the context of what’s behind it; a wide-ish river being funneled through a concrete construction, it makes sense to be careful about the currents. But void of any context it looks completely different:
“⚠️ Interdimentional portal Ahead ⚠️”
This is mildly interesting.
That said, my first thought seeing that sign was quicksand.
Reminds me of the Tsunami signs in the PNW
Low head dams are known as “drowning machines” for a very good reason
https://www.weather.gov/ind/LowHeadDamPublicSafetyAwarenessMonth
There are some downing machine signs that don’t mess around with getting their point across.
“Huh, can you actually risk a certainty…? YUUUURRGKdrown”
Warning: Aperture Science Enrichment Center Main Entrance.
Man eating Black Hole ahead, watch out!
You don’t want to get too close to the world drain.