In certain very specific situations, one’s life could very much depend on a watch, especially when it comes to environments humans are not good at surviving without support. And this is where tool watches can, literally, play a vital role. Plunging ourselves into the depths of the ocean, for instance, is a fine example of where we need a little assistance. Throughout history, the dive watch has evolved from a simple time-only watch to a state-of-the-art computer. There are some though, that can be labelled iconic, such as the Citizen Aqualand. Known as the first dive watch in the world with an electronic depth meter, it revolutionised diving. Now, four decades on, Citizen honours that feat with the rather cool Aqualand Promaster 40th Anniversary…