How Does a Bezel on a Dive Watch Work?

A watch bezel is the outer ring of material that holds the transparent glass pane of the watch (called the watch crystal) in place. The bezel can be used to fix the glass in place, have a decorative purpose, or be used as a functional item like a timer for a dive watch. This article will look at the functional purpose of a bezel for a dive watch and explore some of the mechanisms behind this innovative functionality.

When Was The Dive Watch Bezel Created?

A watch bezel got its name from a type of jewellery setting used when a jewel is set into a ring. They were initially functional pieces used to fix the protective glass for the watch in place. Rolex first explored the bezel as a decorative piece in the early 1930s. Still, it wasn’t until divers started using watches as a vital piece of diving equipment that the bezel became considered for a more functional purpose.

The dive watch was first conceived in the early 1920s with the Rolex Oyster. The team made the watch crystal and the outer casing watertight, protecting the timepiece from water damage and enabling it to go underwater. The Rolex Omega was the first watch to be precisely known as a dive watch.

However, one of the critical features missing from these early dive watches was the ability to calculate the individual’s length of time underwater. The bezel was identified as a way of integrating a countdown timer into the watch functionality to help divers carry out their oxygen calculations and stay underwater for safe periods of time.

The need for a dive watch bezel was fortified during the war with the first deployment of underwater units, Frogmen, responsible for destroying enemy naval vessels. The military equipment had several shortcomings, such as calculating oxygen time. The equipment had also started to filter into popular sports like scuba diving.

The French Ministry of Defense continued to train covert underwater units but repeatedly came up against the timekeeping shortages of the current equipment. They tendered out their watch requirements, and Blancpain, a watchmaker with origins in the 1700s, secured the tender to create the first dive watch with a bezel. Blancpain was the first to release the rotating bezel with the Blancpain Fifty Fathoms.

Diver watch case part closeup on white background. Bezel is black and scratched. Glass is cracked.

What Does A Dive Watch Bezel Do?

Early dive watch bezels could rotate in both directions, which could be dangerous when carrying out oxygen calculations. A simple knock during a dive could mean that the bezel rotated in the wrong direction, ruining the original calculations and even proving dangerous for the diver if they were still underwater when their oxygen ran out.

The unidirectional bezel was created in 1954, meaning there was no risk of a knock during the dive, accidentally extending the dive time beyond the oxygen limit. The unidirectional bezel meant that if the watch was knocked, the only risk was that the dive time would be shortened so that the diver would come up earlier and within the oxygen timeframe. The bezel can only turn counterclockwise during rotation.

How To Set A Dive Watch Bezel

Detail of watch machinery.

You can set a dive watch bezel by following these steps:

  1. Rotate the bezel counterclockwise until the arrow is level with the minute hand of your watch. This signals the start of your time underwater.
  2. To know how much time has elapsed, look at where the minute hand points to. If it points to 20, it means you have been underwater for 20 minutes or that item has been completing an action for 20 minutes. Divers used this to calculate their ‘bottom time’, how long it took to reach the bottom before their ascent.
  1. If you are trying to use the dive watch bezel as a countdown timer, you will instead need to set the minute hand to the number of minutes you need to count down from. If you only have 35 minutes of dive time left, you set the 35-minute marker to the minute hand. Your time is up when the minute hand points to 0.

Divers used to calculate the remaining dive time by subtracting their oxygen time (e.g. 60 minutes) from their bottom time (e.g. 25 minutes) to get the remaining time of 35 minutes.

What Are The Requirements Behind A Dive Watch Bezel?

The bezel itself has the functionality to rotate counterclockwise. It is demarcated with minutes and has an arrow to help you align the bezel. 

The ISO 6435: 2018 have specific requirements about the diver’s watch that impact the bezel, including:

  • It must have adequate readability within 25 cm in total darkness
  • An indication that the watch is operating in darkness, like luminous hands or bezel markers
  • Clear minute markings at the 15 and 20-minute intervals to help calculate dive time.

Many modern dive watches serve the purpose of a timer, which means that they often have non-standard bezel markings like consistent minute markings.

The Rotating Bezel: Modern Innovations

The rotating bezel is a style feature that appeals to many watch enthusiasts today. Smartwatches have also started to adopt the rotating bezel, with the new Galaxy Watch 6 featuring a physical rotating bezel to accompany the digital features. Many popular luxury brands like Tag Heuer and Breitling have the rotating bezel as a firm feature of their offering today.


The rotating bezel became a must-have feature for covert diving units and expanded into the innovative diving equipment we use today for scuba enthusiasts worldwide. The technology has yet to be beaten, and the bezel has become a popular feature of luxury watches and even a physical accompaniment to the digital smartwatch.

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