Some numbers are easier to remember than others. James Bond 007, Porsche 911, 130 maxi on the highway. And then there are 6425. These four numbers, unknown to ordinary mortals, but inscribed in the brains of deep-sea watch enthusiasts, correspond to the official ISO standard defining true diving watches. Because is not “diver watch” who wants.

Tissot Seastar 2000 Professional Powermatic 80 watch. Automatic movement with 80 hour power reserve. Black wave pattern dial (available in light blue and dark blue). Helium valve at 9 o’clock. Rubber strap. €1,025. © DR

To be authorized to carry this precious label, a timepiece must have a list of technical characteristics as long as a summer day without sun. In essence: waterproof to 100 meters; time control system (usually a unidirectional rotating bezel, external or internal, bearing a graduated scale up to 60 minutes); luminescent indexes visible in the dark with a marker at 12 o’clock; operating indicator proving at a glance that the mechanism is working normally (the seconds hand can play this role); screw-down or locking crown; antimagnetic and shockproof protection. And this is only a summary. Good news for aficionados of the Swiss house Tissot, the Seastar 2000 Professional Powermatic 80 is ISO 6425 certified and is even especially aimed at professional divers thanks to its water resistance to 60 bars (600 meters) and its helium valve. With its diameter of 46 mm and its adventurer look, this queen of the great depths rises to the top of the Seastar collection.

Montre Tissot Seastar 1000 Powermatic 80. Mouvement automatique. 775 €. © DR

But an obvious question arises: what’s the point of having a watch intended to face the abyss when swimming in a pool, river or along a beach? The answer follows an implacable logic: who can do more can do less. Because one detail is to be known: the figures are misleading and a water resistance of 3 bars (30 meters) actually only protects against splashes. In fact, a simple shower jet a little brisk could drown the case. To swim serenely, it is necessary to choose a watch capable of dealing with a pressure of at least 5 bars (50 meters). And as we have seen, only a water resistance of 10 bars (100 meters) will open the doors to the world of diving watches. If a model such as the Seastar 2000 Professional Powermatic 80 mentioned above protects against any incident, many waterproof watches are sufficiently waterproof for the vast majority of users. Precisely, Tissot advocates the Big Blue for all by declining its Seastar range in different versions. Starting with the 1000 Powermatic 80 equipped with a 43 mm case waterproof to 300 meters, offered at a very reasonable price.

Montre Tissot Seastar 1000 Quartz Chrono. € 565. © DR

Even more accessible, the Seastar 1000 Quartz Chrono combines comfortable water resistance to 300 meters with the dynamism of a chronograph function. The look is as impressive as it is sporty with a diameter of 45.5 mm, three additional counters clearly visible in the heart of the dial and a rotating aluminum crown marked in red to warn of the last 20 minutes of diving. Justified for security reasons, this colored arc reinforces the visual presence of the watch on the wrist.

Montre Tissot Seastar Lady White. € 445. © DR

In its ambition to respond to all requests in the field of underwater watches, Tissot has added a version intended for small wrists to its Seastar collection. Despite its diameter reduced to 36 mm, this version displays the same water resistance to 300 meters as its big sisters, naturally has a unidirectional rotating bezel and offers the extreme precision of its quartz movement. It also has an end of battery life indicator. On the aesthetic side, this Seastar 36 mm plays the beauty of the depths with its dial available in white, blue or black lacquer and with its interchangeable bracelet, metallic or silicone. Ready to dive, as the submariners say.