A sonarmen is a person who works with sonar, a tool that uses sound to find things underwater.
Sonarmen are often thought of as skilled and important because they help find things underwater.
Examples:
The sonarmen use special tools to find things underwater.
My uncle is a sonarmen and he finds old ships.
The sonarmen found a treasure under the sea.
The sonarmen can find fish with their special tool.
The sonarmen found a giant octopus with their special tool.
The sonarmen are like underwater detectives, finding things no one else can.