Although Doxa produces a fairly wide assortment of dive watches, the cushion-shaped profile of the classic SUB 300 is easily the brand’s most famous design, and it serves as the foundation for a significant portion of Doxa’s modern catalog. Alongside models in smaller and larger formats, and even some with forged carbon cases, Doxa also produces the SUB 300 Beta collection (sometimes listed as the SUB 300β or SUB 300B), which first debuted last year in 2023. While the Doxa SUB 300 Beta still adheres to the familiar cushion-shaped design established by the brand in 1967, it features a slimmer profile and more refined styling to create a less tool-oriented expression of Doxa’s signature dive watch.

At the time of writing, the Doxa SUB 300 Beta collection spans five variations from the brand’s usual spectrum of colorways, and these include Professional (orange), Searambler (silver), Caribbean (blue), Divingstar (yellow), and Aquamarine (turquoise). With that in mind, rather than having dials completely finished in these colors like most of its watches, the SUB 300 Beta models primarily incorporate their colorways in the form of small accents, and it is only the Caribbean and Searambler models with dials that actually appear in their respective colorways, with both versions also featuring small orange highlights. The remaining three models from the SUB 300 Beta lineup are all fitted with black dials, and their use of color is limited to small accents throughout their dials, hands, and bezels.

Crafted from 316L stainless steel, the case of the Doxa SUB 300 Beta features circular brushed top surfaces with high-polished sides, and it measures 42.5mm in diameter by 11.95mm thick, with 20mm lugs and an overall lug-to-lug profile of 44.5mm. While the SUB 300 Beta has the same dimensions as the Doxa Army, the two watches are very different offerings from an aesthetic standpoint, although it is highly possible that they share the same cushion-shaped middle case. Since the SUB 300 Beta is intended to be a more refined version of the brand’s famous dive watch, its case is thinner than models from both the SUB 300 and SUB 300T collections, and because it has the same outer diameter, it ultimately wears noticeably flatter and lower against the top of the wrist.

Despite having a thinner profile, the Doxa SUB 300 Beta offers the same 300 meters of water resistance as the standard SUB 300 collection, and the weight of the watch comes in at approximately 79 grams (without a strap or bracelet). While a thinner profile makes perfect sense for an elevated twist on the brand’s classic diver, Doxa has rather curiously decided to include a helium escape valve on the 9 o’clock side of the SUB 300 Beta’s case, and this is a particularly puzzling detail since the model is intended to be a less performance-oriented offering and helium escape valves are exclusively required for the most advanced forms of commercial saturation diving.

The top of the Doxa SUB 300 Beta’s case is furnished by a flat sapphire crystal surrounded by a 120-click unidirectional rotating bezel in the brand’s signature “No-Decompression” style, with a saw-tooth outer rim and a patented dual-scale design that includes both elapsed-time and depth markings. However, unlike the SUB 300 and SUB 300T models, which both feature steel bezels, the Doxa SUB 300 Beta watches have their bezels crafted from ceramic, with their brightly colored depth markings serving as the only departure from their otherwise monochromatic appearances. A solid screw-down caseback closes up the reverse side of the SUB 300 Beta, while a black ceramic screw-down crown sits partially recessed into the side of the case at the 3 o’clock position, and it is signed with Doxa’s fish emblem to match the colorway of each watch.

The dials fitted to the Doxa SUB 300 Beta collection follow the same general layout as the brand’s SUB 300 and SUB 300T watches, although they represent a rather significant aesthetic departure compared to Doxa’s usual offerings. In addition to featuring a sunburst finish, the dials also have a horizontal wave texture embossed into their surface, which provides them with a more dynamic and refined overall appearance that creates lighter and darker hues that move within the light. Aside from their surface finishing, the SUB 300 Beta dials otherwise adhere to the same overall blueprint as the brand’s other models, and they feature luminous hour markers, an oversized minute hand, and a date window at the 3 o’clock position.

Just as you would expect from a dive watch, all of the hands and hour markers on the Doxa SUB 300 Beta watches are luminous, and they receive an application of Super-LumiNova to provide them with an aqua blue-colored glow in the dark. Due to the printed design of the indexes and their relatively small size, the actual amount of luminous material on the hour markers is fairly minimal, which means that the SUB 300 Beta doesn’t glow quite as long or as brightly when compared to other dive watches that have large applied hour markers that are entirely filled with Super-LumiNova. However, the ultra-legible design of the dial combined with its luminous markings ultimately provides more than enough visibility to allow easy access to the time in dark environments.

Powering the Doxa SUB 300 Beta collection is the Sellita SW200 automatic movement, which is the same caliber that the brand uses inside nearly all of its three-handed models (although Doxa rarely actually lists movement details on its official website). Running at a frequency of 28,800vph (4 Hz) with a power reserve of approximately 38 hours, the Sellita SW200 is the definition of familiar and inauspicious, and it very well might be the single most common Swiss mechanical movement in the industry. However, this rather ubiquitous caliber is also an extremely proven design that is used inside countless watches from a wide variety of brands, and it ultimately makes a highly practical choice for a straightforward three-handed dive watch.

Just like other Doxa models, the SUB 300 Beta is available with either a stainless steel beads-of-rice bracelet or a rubber strap that is color-matched to the dial of each watch. The bracelet features completely solid components with single-sided screws for the removable links, while the straps are made from FKM rubber and have molded ends that fit the shape of the case. The strap and the bracelet both connect to the 20mm lugs and immediately flare out to 23mm to meet the edges of the case, before tapering back down to 20mm where they attach to their signed stainless steel folding clasps. Additionally, the same exact clasp is used for both the rubber strap and bracelet, and it operates with a double push-button release and an integrated extension system that offers seven positions of incremental adjustment.

While Doxa’s straps and bracelets are typically quite well-constructed offerings, I’m personally not the biggest fan of their proportions, and they always end up feeling a bit too large and bulky relative to the cases of their respective watches. For example, while the bracelet links do taper, they taper back down to the same 20mm width as the lugs to compensate for the way that the first link flares out to meet the edges of the case. Furthermore, the clasp itself is 22mm wide, which means that the bracelet ends up being a fairly chunky presence around the entire circumference of the wrist. Similarly, Doxa’s rubber straps feature a cut-to-fit design, and while many other brands also follow this same approach, I personally find it rather short-sighted that you cannot ever increase the length of the strap in the same way that you can simply add links back into a metal bracelet.

While I very much enjoy the overall concept of the Doxa SUB 300 Beta series, I ultimately wish that it leaned a bit harder into its refined design ethos to create something that represented a further departure from the various other divers that currently exist within the brand’s catalog. While the case profile of the SUB 300 Beta is thinner and its dial is noticeably more intricate, the watch itself isn’t different enough from the SUB 300 and SUB 300T that it would open the series up to an entirely new demographic of buyers in the same way that the brand’s SUB 200T watches do this with their midsize cases. Additionally, the inclusion of a helium escape valve on the SUB 300 Beta just feels like a bit of a misstep, as this is one of the most specialized and seldom used features in the world of dive watches, and it completely goes against the less professionally-oriented theme of this particular series.

Although I would have personally liked to see the Doxa SUB 300 Beta take the concept of this collection even further, it is important to remember that the purpose of the SUB 300 Beta isn’t to be a completely new timepiece but rather to be a more elevated version of the brand’s most recognizable model. Due to its ceramic bezel and more intricately finished dial, the Doxa SUB 300 Beta costs slightly more than the SUB 300T, although it is also less expensive than the SUB 300, which features a domed crystal and a chronometer-certified movement. Positioned directly between its two siblings within the catalog, the Doxa SUB 300 Beta is accompanied by an official retail price of $2,250 USD on a rubber strap, or $2,290 USD when paired with a stainless steel bracelet, and while it is still instantly recognizable as being part of the greater SUB 300 family, the SUB 300 Beta ultimately succeeds in being a more refined version of the brand’s single most famous model. For more information on the Doxa SUB 300 Beta, please visit the brand’s website.