Tool watches, the industry term for durable timepieces used for specific purposes, such as diving, excite collectors and enthusiasts with their sophisticated functions and built-in instruments.

But what do people who rely on these watches in their everyday lives wear on their wrists?

For Morten Paulsen, who works with underwater remotely operated vehicles, also known as R.O.V.s, the watch of choice is a JSAR diver’s quartz model by Marathon, a Canadian brand of Swiss-made military timepieces.

Because smartphones and devices containing combustible substances like lithium are forbidden in many of the control rooms, vessels and areas where Mr. Paulsen and his teams work, a sturdy, reliable watch is essential for telling the time.

“And it has to be waterproof,” said Mr. Paulsen, an employee of BSA, in a telephone interview. The Norwegian company provides services and maintenance to underwater installations around the world, among them pipelines, oil rigs and offshore energy plants.

In his line of work, a watch can easily become drenched by water that runs off the vehicles when they are retrieved from the ocean, often from depths of up to 3,000 meters, or 9,850 feet, below the surface.