When diving deep into the mysterious depths of the ocean, your bezel can be a lifesaver. Let me explain why.
When diving with oxygen tanks, it’s extremely important to keep track of time. The oxygen gauge of your tank is strapped tightly to your back, so you can’t just take a quick peep to see how much air you still have left in the tank while strolling on the bottom of the ocean. You have to time everything neatly and control your breath.
How do we solve this problem?
Since very few chronographs are water resistant, and sub dials are too small to read under water, the bezel on your dive watch is used.
If you align the 0 of the dive bezel to the minute hand when you hit the water, you can see how long you have been under water in the blink of an eye. The marks on the bezel indicate how long you have been under water, and how long you have been using your oxygen tank. The bezel is mounted on the case of your watch and is not connected to the movement. This means that it can be used under water without compromising the waterproofness of your watch. Operating for example your crown under water will turn your watch into the Titanic 2.0.
So in short: Neatly tracking your time under water is a literally a matter of life and death.
Now imagine this: you are timing your dive, and mid-dive you jam you watch into an object and the bezel turns without you knowing. Miscalculating the oxygen in your tank might result in injury or worse!
Enter the bezel lock. By pushing this button, the bezel locks into place and can't be turned in any direction.
To have a button that can be operated under water in pitch black conditions while wearing thick gloves, the button has to be easy to operate and easy to find. The Omega Ploprof might be the best and most famous example. The big colorful bezel lock button can easily be operated with gloves, and the bezel in fluted in a particular rugged way to maximize grip in the same slippery conditions. To ‘one up’, the Ploprof has a shark mesh and a fully protected crown. Crown guards protect a crown, but a fully shielded off crown takes away every risk.