Jumping in the pool, it's normal to take off your watch; jumping in the sea to swim underwater and you'll need to know the key features of scuba diving watches and how to use them.

Telling the time underwater can save your life. Image: Flickr/ Vidar - Aqua-Photos.com

Scuba diving watches are typically chunky, analogue affairs with large crowns and distinctive bezels - yet there's much more to the wrist wrappers than first meets the eye...

Before you buy, don't be deceived by big names - and equally large price tags - keep your eye on the specs we list below and buy the watch you need, not the model others might like to have popping over their shirt cuff on their way to work.

For some people a dive computer will be enough. But, as a reserve measure of time, you can't beat a reliable diving watch.

Like their premium dive watches, all models need to have some basic features in order to survive under the added pressure.

Let's have a look at the 3 key features of scuba diving watches:

The Folding Link

Any introduction to scuba diving equipment will include all the technical gear, as well as the less complicated - but equally important items - such as wetsuits, booties, fins etc.

Most watches featured will have a very simple modification which allows for their use underwater: The folding link.

To extend the strap around your wetsuit sleeve, you'll need to have this extra 'folding link'. It folds away into the clasp and unfolds when you need it. What it does is lengthen the strap so it's got the reach to go around your wetsuit sleeve.

Rubber straps don't need this feature, as all you have to do is let the strap out a hole or two. That said, rubber straps perish and weaken, so many divers opt for the longer metal straps.

Rolex Submarine Two Tone. Flashy, well featured, but would you really dive with it?

Large, uni-directional rotating bezel

If you are buying a dive computer, you'll see that they look just like watches - in that they have a strap and sit on your wrist. Some you could even confuse with a watch, unless of course they are analogue...

An analogue divers watch will need a large face and a prominent dial. The bezel is the piece that you can turn independently of the watch. You use the bezel and line it up with the watch hands giving you a very basic countdown timer - and one that 's not likely to go wrong.

This method is not used as a technical, exact measurement of time, more a guide - and they are very much a defining feature of diving watches. Look here

And check the bezel only turns in one direction!

Clear Face and Units

There are digital diving watches on the market, but it's easy to see why most divers at this online watch shop tend to go with the traditional, analogue style: it's because they are extremely easy to read.

Large luminous markings and solid watch arms help identify time in darker environments.

And if you get yourself an automatic model, you'll never need to buy batteries again!