Teddy Baldassarre
What is 5 ATM Water Resistance? Watches’ Depth Ratings Explained
Watches differ widely not only in their designs, materials, and functions but also in their ability to resist the detrimental effects of water and moisture. Some watch enthusiasts, especially those who wear their timepieces for diving, know exactly what they're looking for in terms of waterproofing, but many others might be unsure exactly how safe it is to wear their watch in the swimming pool or even to wash the car. What do watches' water-resistance ratings like 5 ATM or 10 ATM mean in the real world, and how exactly do industry terms like "bars" and "atmospheres" help you determine how waterproof your watch is? Here we address some commonly asked questions about water resistance in watches and break down what the most common depth ratings mean in practical terms. What was the first water-resistant watch? Since the invention of the wristwatch, watchmakers have been coming up with solutions to address an inconvenient reality: namely, that water and tiny mechanical parts, such as those inside a watch movement, simply do not mix. The technical challenge of making a portable timepiece that could withstand exposure to water became even more prominent in the mid-20th Century, with the rise of diving as a tactical and eventually also a recreational pursuit. The first innovator to seriously take up the gauntlet was Rolex founder Hans Wilsdorf, who developed the now-famous Oyster case in 1926. Its groundbreaking design combined a threaded, hermetically sealed caseback and a cro...
