Among significant watches, the quartz-driven SBBN015 is a top pick! Look at it from a historic point of view or with respect to the metal and the rest of the materials, there’s nothing that can probably demoralize you on professional specifics. Sounds too much? Well, calling it the Tuna at the first place would have done it all!

Tuna - The lineage leaves nothing to be explained further; this substantial hulk of a watch is also a quintessential equipment for the serious diver, with a weight (near to a quarter of a pound) that won't give you a tennis elbow. Great attention was put into its refinement and the perfect weight is just one example of the masterful craftsmanship. There’s difference between heft and weight; the masters at Seiko understand that well! It also makes the Tuna a safe watch to wear around children.

At 48mm diameter, it might seem big but it’s surprising the way it fits even medium sized (6.5-inch or a bit less) wrists and feels absolutely balanced! The secret here is a shorter distance between the lugs; this turns this rather large watch into a reasonable, diver-watch.

The dramatically curved, Hardlex crystal holds excellently against shattering forces and better than sapphire. This has a disadvantage though; you’ll gather no proof for your war stories. A clear, eye-catching bubble, specially created to ward off reflections way more than flat crystals, but then again, the little bit of reflection it gives off only accentuates the beautiful curve of the crystal.

The dial has some text that give off more of a professional aura and therefore, a serious look; MARINEMASTER itself is a mesmerizing name. The simple markers enhance the overall beauty and legibility of the face, but imparts a complex, instrument kinda look to the Seiko Chrono watch when on the wrist. Most of it comes from the visible stainless steel between the chapter ring and the bezel insert; the notched, stainless steel bezel and around it the brushed shroud add the necessary flavor. Furthermore, the hex-screws and a ridged crown add to the watch the steroid-like effect. They bring greater attention to details and also, a fair bit of industrial temper. The only polished area in the entire Seiko Chronograph Watches is its caseback. It reads He Gas Diver that can go down till 300m with ease. This is deeper than most will need to go, so hold your panic for a long time to come.

So now, to the movement. The 7C46 is an extremely reliable, multi-jeweled, thermal-insulated movement that’s built very, very ruggedly and completely out of metal components. It handles the rigors of extreme deep saturation diving very well. The high-torque tolerances makes it high on efficiency and comprises a 7-jeweled geartrain, whose pinions move the hands perfectly synced to the energy-pulses. This requires much less kinetic efforts from the electronic step motors, resulting in highly accurate timekeeping.