Under which condition might a drowning person go unnoticed?

A drowning person may go unnoticed in murky water because visibility is significantly impaired, making it difficult for lifeguards and bystanders to see someone in distress. Murky water can hide both the individual and their struggles, leading to a situation where signs of drowning, such as flailing or the person calling out for help, could be obscured. In environments where visibility is compromised, it becomes crucial for lifeguards to be vigilant and proactive, as the risk of unnoticed drowning incidents increases.

In contrast, surrounding conditions like being surrounded by people, splashing, or wearing a life vest can often draw attention. Being surrounded by others may lead to someone's struggles being noticed more easily, while splashing can signal distress. A life vest may keep an individual afloat, making it less likely for them to drown unnoticed, although it does not eliminate the risk entirely if they are incapacitated.