People who work in submarines, especially as part of the crew.
Submariners are skilled and brave because they work in a very special and sometimes dangerous place.
Examples:
The submariners operate the submarine deep under the water.
The submariners are trained to handle emergencies in the submarine.
She wants to be a submariner when she grows up.
The submariners have to be very careful not to bump into things underwater.
The submariners are like underwater astronauts, exploring the deep sea.
The submariners are the heroes of the deep, like mermaids but with mustaches.