Introduction Seamaster is one of the flagship collections from the Swiss luxury watch brand Omega. This best-selling series comprises various sub-collections, ranging from heritage-inspired classic timepieces to modern tool watches. The prominent among them are Diver 300M, Aqua Terra 150, Planet Ocean, and the Heritage series comprising models like Seamaster 300, Railmaster, Ploprof 1200M, Bull Head and Seamaster 1948. The origins of the Omega Seamaster family date back to 1948 when the iconic Swiss company introduced a wristwatch endowed with ruggedness, reliability and superior water resistance. Named Seamaster, this historic timepiece represents a culmination of the brand’s expertise in manufacturing robust and precise military watches. The first modern diving watch from this magnificent collection, the Omega Seamaster 300 Diver was launched in 1957. The iconic seahorse (hippocampus) symbol on the case back of the Omega Seamaster was introduced in 1958. Certifying the aquatic nature of this collection, it is one of the most distinguished icons from the Swiss watch brand. Thanks to its enduring partnership with the James Bond movie franchise since 1995, this timepiece collection has millions of ardent admires from all over the world. The brand has also created several special edition Omega 007 Seamaster models inspired by the world’s most handsome spy. From the name, many people may think that Seamaster 300 and Seamaster Diver 300M are the same watch. In fact, they are two distinct watch models from the series. In this article, we are comparing them in terms of design, case, dial, movement and bracelet. Omega Seamaster 300 Pic from: omegawatches.com Devised especially for underwater adventures and exploration, the original Seamaster 300 watch stands out with its robust case design, diving bezel, and luminescent coated hands and indexes. Presently, the brand is offering its new generation models from the Heritage series. Available in two case sizes (39mm and 41mm), these watches feature a metal bracelet or leather strap. The Omega Seamaster 300 is offered in steel, bi-metal (steel with gold), 18k gold, platinum and titanium versions. Depending upon the version, they feature solid-metal or sapphire crystal case-backs. Omega Seamaster Diver 300M Pic from: omegawatches.com This contemporary diving timepiece was introduced in 1993. Evolved since then by adopting new technologies and materials, it is one of the most popular dive watches in the world. The available case sizes of standard models, no matter with or without date, are 42mm and 43.5mm. The chronographs are offered in 41.5mm and 44mm versions. These models are equipped with automatic movements, and depending upon the generation they come with the chronometer or master chronometer certification. For ladies, the brand is offering a 28mm version with quartz movement. The Omega Seamaster Diver 300m is available in steel, 18K gold, steel with gold, ceramic, platinum, tantalum and titanium versions. They are fitted with solid metal or sapphire crystal case-backs. Seamaster 300 Vs Seamaster Diver 300M Seamaster Diver 300 M (1) Design The Seamaster 300 has a vintage-oriented design evoking the brand’s rich heritage in manufacturing submersible watches whereas the Seamaster Diver 300M has a contemporary outlook. The former is a collector’s delight and the later is dedicated to professionals and modern tool-watch enthusiasts. (2) Case Both watches feature solid case construction for steadfastly maintaining the water-resistance rating of 300 meters (1,000 feet). There are a number of notable differences between the cases of both models. Both Seamasters are equipped with unidirectional rotating bezel, a necessary component of contemporary diving watches. The Seamaster 300 is fitted with a round, coined-edge bezel featuring a thin bezel-insert made of anodized aluminium or ceramic. The Seamaster Diver 300M comes with a so-called facetted bezel with a broader insert in metal or ceramic. The Seamaster 300 comes with tapered lugs as seen in the vintage references. The lug-width is 21mm for the 41mm variants and 19mm for the 39mm models.  The Omega 300M Seamaster Diver features the so-called twisted lugs, perfectly harmonizing the design of the bezel. The lug-width is 20mm for the models with 42mm diameter case and 21mm for the 43.5mm versions. Moreover, the Omega Seamaster Diver 300M watch is equipped with protective features like the helium-release valve at 10H and crown guards. The Seamaster 300 does not have these safety measurements.  (3) Dial SEAMASTER 300 The Seamaster 300 is available with black, blue, brown and semi-precious stone (lapis lazuli or malachite) dial versions. The 60th Anniversary Trilogy models come with black tropical dials. Whereas the regularly produced Seamaster Diver 300M watches feature wave-pattern dials. They are available in color choices like black, blue, green, grey and white. The 42mm Omega Seamaster 007 model comes with a tropical brown dial, while the James Bond Edition has a spiral-brushed black ceramic dial. The Seamaster 300 watch stands out with its broad-arrow hour-hand and dauphine minute-hand. The models from the new Omega Seamaster 300 2021 range are fitted with a lollipop or spear-shaped centre seconds hand. In comparison, the Seamaster Diver 300M features two open-worked sword hands (hour and minute) and a lollipop centre seconds hand. The Seamaster 300 comes with triangular hour-markers and additional Arabic numerals at cardinal points (12, 3, 6 and 9). The Seamaster Diver 300M has bold-sized rectangular and dotted hour-markers. In addition to the above, the beige-colored luminescent material applied on the hands and markers of the Omega Seamaster 300 evokes the style of vintage tool watches. The Seamaster Diver 300M has a white luminescent coating, which is comparatively modern. In both cases, the Super-LumiNova pigment offers attractive blue or green radiance in the dark. (4) Movement The automatic watches from the Seamaster collection are equipped with co-axial calibers. The 41mm Seamaster 300 models with sand blasted black or blue dial feature the Cal. 8912 for the references launched in 2021 or Cal. 8400 in case of its predecessors. The 39mm models from the 60th Anniversary Trilogy series are driven by the Caliber 8806. Released in 2019, the 41mm Seamaster 300 watches with semi-precious dials are powered by the caliber 8913. Displaying the date at 6 o’clock, the 42mm Seamaster Diver 300 is equipped with the calibre 8800/8801. The “time only” variants in 42mm and 43.5mm cases utilize the caliber 8806/8807. These self-winding movements with co-Axial escapement offer impressive resistance to magnetic fields greater than 15,000 gauss. They also provide a 60-hour power reserve. (5) Bracelet Currently, the Seamaster 300 is available with two strap choices: A three-link metal bracelet and non-grained leather (calf or alligator) strap. They come with fold-over clasps. On the other hand, the Diver 300M is offered with strap options like rubber, fabric, metal (five-link), mesh and leather. The five-link metal bracelet features a comfort setting and diver extension. The rubber strap comes with a pin buckle.