Ratio FreeDiver Professional 500M Sapphire Automatic 32BJ202A-BLU Men's Watch 

It monitors how long you’ve been underwater, and - more importantly - how much air you have left till you surface. It is a fashionable and useful, quintessential dive watch but without that immediately recognizable look. It’s built like a tank, easy to read and it looks just plain cool. The sapphire glass is an added bonus at this price.