Hands-On Bremont S300 Supermarine Kaimu 40m Dive Watch – Serious Diver Durability & Timeless Aviation Vibes

The Skinny

  • 40mm
  • Modified Calibre 11 1/2’’ BE-92AV (Sellita SW200 base) auto-winding with date
  • 300m water resistance
  • Year of release: 2022
  • Precision: retail models will run within COSC Chronometer specifications (-4/+6 secs/day)
  • Kaimu is a black sand beach in Hawaii
  • $3695

A Family of Classic 40mm Divers

I like relatively smaller watches, so I was delighted when Bremont introduced its 40mm S300 Supermarine dive watch range in 2017. I’ve owned the Supermarine S301 Black since then, and it has been my favorite dive watch ever since – and I own many. For more on why I find Bremont to be an excellent yet too often misunderstood brand you can read my thoughts here.

Since 2017, Bremont has regularly iterated on the S300 range, and the successful results show us that the core design is a classic. This comes down to traditional dive watch proportions, such as bezel-to-dial ratio, diameter, height and lug-to-lug dimensions, a reasonably sized crown without guards, and a legible dial layout. As the saying goes: it’s a classic for a reason. These proportions were well sorted out in the mid 20th century and are, in my opinion, best not tinkered with.

Bremont S300 Supermarine 40mm Dive Watch Line
Bremont has gradually built out the 40mm Supermarine line since 2017.

What isn’t traditional about the Bremont 40mm 300 Supermarine divers is the three-piece Trip-Tick case with its bullet-proof hardened steel, aluminum mid-case insert, and beautifully droopy lugs. It’s a watch that from the front looks entirely traditional but from the side entirely avant garde. Bremont has built an abundance of successful collections around the Trip-Tick case, which indicates that this innovative design is itself destined to become a classic – if it hasn’t already.

Bremont Supermarine S300 40mm Dive Watch Kaimu
Bremont Supermarine S300 40mm Dive Watch Kaimu

A classic already? As of this writing (2022) we are leaving behind a decade of unprecedented watch brand proliferation ranging from micros to indies to big-biz newbies, and Bremont stands strong among the few robust survivors who will claim a lasting role in watchmaking history. It is in this broader context that this new S300 Kaimu is best understood.

A Dressy Dial With Deep Aviation Roots

The S300 Kaimu stretches the boundaries of the S300 range from a sporty and rugged dive watch line to a dressier and elevated aviation-oriented visage.

Bremont didn’t need to change all that much to elevate the S300.

Bremont Supermarine S300 40mm Dive Watch Kaimu with Spuermarine Black S301
An effortless transformation from rugged diver to elegant aviation-oriented timepiece. S301 Black (L) with Kaimu (R).

The engraved dial with plated rose gold markers and hands is an obvious nod to watches of the 1930s, which should not be a surprise given that the Supermarine planes to which these watches are dedicated were also developed in the 1930s. In this sense, the Kaimu’s dial fulfills more fully the Supermarine’s eponymous connection to that all-important era of aviation than any previous S300 model.

Bremont Supermarine S300 40mm Dive Watch Kaimu
Bremont Supermarine S300 40mm Kaimo

However, it really wasn’t until the 1950s that aviation watches became civilian-owned items. The Rolex Air-King started this trend that shed gentlemanly Art Deco decoration in favor of military-grade minimalism. This trend rose after WWII within a rather bored middle class drawn to the edgier styles of work wear and military garb like denim pants, flannel shirts, aviator sunglasses, tee-shirts, and bomber jackets. A watch with a fancy art-deco dial didn’t make the low grade; that was Dad’s watch, maybe even Grandpa’s.

Vintage Rolex Air-King
Rolex Air-King 1954. Image: Sotheby’s.

As such, the kind of dial decoration we see on the S300 Supermarine Kaimu harkens back to an older tradition of aviation, one less concerned with being a badass fighting cowboy of the sky than with being a gentleman pilot – a dandy even. I’m thinking of Santos Dumont here, the Brazilian pilot for whom Louis Cariter made the first ground-up wrist watch years before the Tank – and famously worn by the likes of Yves St. Laurent in the 1970s. I’m thinking of those 1930s Longines sector dial watches that so effortlessly bring elegance and function together. The versatility of the 40mm Supermarine core design is evidenced by how effortlessly Bremont was able to transform the watch to honor that era.

Cartier Santos
A solid gold Cartier Santos.
Vintage Longines Weems
Longines Weems Pilots Watch c. 1930s. Image: Sotheby’s.

A Posh Ceramic Engraved Bezel with Unique Aviation Roots

There’s nothing vintage about the engraved ceramic bezel on the S300 Kaimu, but, interestingly, this style of bezel dates back at least as far as 1954 when Rolex released a solid gold Turn-o-Graph. Essentially a Datejust with a rotating bi-directional timing bezel, the Turn-o-Graph perfectly married sport capabilities and high style, and was something of a throwback in the mid 1950s. Often called the Thunderbird for having been issued to the elite US Air Force Thunderbirds, the Turn-o-Graph remained an aviation-oriented model in the public imagination for decades. 

Bremont Supermarine S300 40mm Dive Watch Kaimu
Vintage Rolex Turn-o-graph
Rolex Turn-o-Graph Ref. 6309 of 1954.

But then things get confusing with Rolex, as they often do when considering the brand after it sent its tool watches upscale during the 1980s and 90s (think pave diamonds and solid gold Subs). The Turn-o-Graph now lends its bezel to the Yacht Master, which was released in the 1990s as a kind of high-style Submariner for the nose-up yachting lifestyle. Unfortunately, it is the Yacht Master with which many will associate the S300 Kaimu’s bezel insert, but (like the dial) the bezel’s roots are more entwined with aviation than one might first assume.

Bremont Supermarine S300 40mm Dive Watch Kaimu with Rolex Yacht Master and Rolex Turn-o-graph
Seen together, the Yacht Master shows itself more as a variant of the Rolex Submariner, and the Supermarine Kaimu more in line with the Turn-o-Graph.

Aesthetic Reactions & Aviation Vibes

I came to adore the S300 Kaimu once I stopped thinking of it as Bremont’s version of the Rolex Yacht Master. If one accepts this watch on its own terms, its strong affiliation with aviation history comes forward. Aviation narratives are important to Bremont as a brand, and these narratives can drive you to deeper understanding of their timepieces. These narratives can quite literally alter one’s aesthetic perception, and I for one welcome anything that can chip away at Rolex’s hegemonic hold on how we see watches. I’ve even characterized Rolex as a Black Hole for this reason.

Bremont Supermarine S300 40mm Dive Watch Kaimu
Bremont Supermarine S300 40mm Dive Watch Kaimu

Stripped of the modern Rolex comparison, I began to see a stylistically elevated dive/aviation watch that harkens back to before WWII, when pilots cut a sophisticated and gentlemanly figure.

The black gator-embossed calfskin strap is probably what I’d have put this watch on anyways, so it’s ideal. I’m glad it’s not varnished with gloss, but semi-matte to match the charcoal color of the bezel and engraved dial. And the black aluminum mid-case insert is a nice colorway tie-in that adds dynamics to the sides of the case where most tool watches remain bland.

Bremont Supermarine S300 40mm Dive Watch Kaimu
Bremont Supermarine S300 40mm Dive Watch Kaimu

But it’s the rose gold against that engraved black dial that brings it all together for me, a perfect colorway for capturing the sophistication of an elegant era – an era I personally wish we indulged more often in our increasingly casual moment. This is a watch I’d wear with suits, to weddings, funerals, restaurants with white tablecloths, or anytime I wanted to go beyond the norms of today’s insistent mid-century casualness to embrace a more timeless elegance.

And the white version, called Vigo? Maybe not my vibe, and maybe aimed more at women in some gender-normative sense, but that’s a trip for another time.

Bremont Supermarine S300 40mm Dive Watch Kaimu

And Finally The Movement

My S301 just came back from service at Bremont’s Wing factory in England, and it is running dead square within COSC tolerances (-4/+6 secs/day). It ran about that well for years of abuse on motorcycles, while skiing, diving, and just being a clumsy guy who wore it constantly. These movements are adapted from ebauche-grade Swiss Sellitas, and include 25 jewels, Glucydur balance wheels, Anachron balance springs, and Nivaflex mainsprings.  Along with the hardened case, the COSC-certified precision is impressive, and should help anyone understand why Bremont remains one of the strongest young brands today – literally and figuratively.