Dive watches are a relatively new invention in the world of watchmaking. While they have been around since the 1950’s (or before), dive watches began to be a popular consumer item in the 1960’s.

When an activity called SCUBA ( Self-contained underwater breathing apparatus) diving was on the rise in the 1960s, the horological industry was working to create watches that would accommodate the needs of its enthusiasts. 



Since their early days, dive watches have become a popular tool-slash-timepiece as the ability to time the dive was crucial to every diver. In that era, most watchmakers around the world raced to produce dive watches. 

Among the huge brands like Rolex or Omega that made their mark in the early days of SCUBA, Seiko also started producing high-end professional diver's watches. Many of these early models have become icons, and there are some great Seiko diver models that are on the market today.  


What is Seiko PROSPEX?

Since the launch of their original Seiko dive watch, the 6217, Seiko has been manufacturing all sorts of watches dedicated to the sport ranging from affordable quartz pieces to robust high-end automatics. 

Today the PROSPEX line features numerous models that are water resistant to 200m - or more. The name PROSPEX simply means “Professional Specifications” which become more obvious when using the watch. 


Better specs for the demanding watch wearer. Source: Monochrome Watches


As the name implies, these watches are an answer to the professional world where performance matters. The build quality of this line of watches is world class, and use cutting-edge technology.

In addition, Seiko’s PROSPEX line has debuted some industry leading innovations. These innovations include the first dive watch with a titanium case, the first to use a quartz movement in a professional dive watch, and the first to use a ceramic shroud.

All of these pieces are powered by Seiko’s own in-house movements which are widely regarded as among the best in the industry.

To show what makes the PROSPEX line worth buying, let’s look at 5 of the most iconic pieces of Seiko’s PROSPEX line!


The SRPC93 - “Save The Ocean” Samurai

Loads of collectors are looking for Seiko models that were mostly available only in the domestic Japanese market. The Seiko PROSPEX SRPC93 is a model that demanded the attention of collectors. 

The SRPC93 is from the Seiko Prospex “Save the Ocean” limited edition collection. It features a blue dial with an organic horizontal pattern which takes inspiration from the ocean. Like all of the Samurai models, it uses a 43.8mm wide and 12.8mm thick case, while featuring a water resistance of 200m.


Beautiful and with purpose. Source: A Blog to Watch


The 4R35 movement inside has the modern features that watch lovers expect like automatic winding, hand-winding, and hacking. It operates with a power reserve of 41 hours.

In addition, Seiko supports a marine conservation charity to highlight its dive watches. The brand donates a portion of the sales proceeds to the non-profit Fabien Cousteau Ocean Learning Center.

These watches work well, look great, and help the planet! 


The SBBN031 - Marine Master Professional 300M “Tuna”

The SBBN031 hails from one of Seiko's most successful PROSPEX lines, the Marine Master Professional, which is more famously known as the “Tuna”. 

As one of the latest members to join the “Tuna” family, the SBBN031 features a 48mm wide case that is approximately 14.7mm thick. The case and shroud are made from  stainless steel, and it packs a  7C46 7-jeweled quartz movement.


Divisive looks but we all agree it's great as a diver. Source: Random Rob


The Seiko Tuna line is 100% an original innovation by Seiko, and is widely used by professional divers thanks to its very high water resistance and solving multitudes of problems faced by divers.

The SBBN031 is the successor to the SBBN015, which was the long-beloved benchmark of the quartz-powered Tunas. This watch is all business, and isn’t made to fit under a cuff!


The SRPD27 – A ”Monster” Watch

Another model from Seiko that can’t be ignored is the SRPD27. If you are looking for a sporty and robust dive watch with great performance and a unique design, this model may fit you perfectly. 

The “Monster” name refers to a collection of dive watches from Seiko that have been around since the year 2000. It is a chunky case with a unique bezel design. The case and bezel measure 42mm in diameter and it has a thickness of 12mm. The lugs are satin-brushed, as are the sides of the case. 


Big energy. Source: Professional Watches


Unlike many Seiko divers, this Monster comes on a rubber strap, and has off-white lume (although it glows like a torch). One point that stands out is the cyclops magnifier, which does make the day and date complication much easier to read. 

It also packs a 4R36 movement, which will work for years without any maintenance. 

Meeting ISO 6425 standards (water resistance is 200m) means the SRPD27 can be used for scuba diving and practically any type of water activity - and can also handle harsh conditions with ease. 

One factor that helps this model appeal to a wide audience is the price. It is one of the most affordable Seiko divers out there, and is well worth the money spent. 


The SRPA21 - PADI “Turtle”

The Seiko Prospex SRPA21 PADI “Turtle” is another major value proposition that also packs 200m of water resistance. It was created to be a vintage-oriented model that takes styling cues from the iconic vintage Seiko 63XX series.


For serious divers. Source: Millenary Watches


With a deep blue dial and red themes, the SRPA21 looks extremely good in this special edition made with PADI, the world’s most trusted scuba diving training organization over the past fifty years. 

The large arrow minute hand painted in red is a specific feature of this SRPA21. This is one of the coolest dive watches out there, and should be on any collectors radar. If it becomes too hot to find (and expensive) there are probably more special editions coming. 

Looking to build a mod that is inspired by the Seiko Turtle? Check out our catalog of Turtle parts here.


The SRPB51 – A Classic “Samurai”

Seiko introduced a new Samurai collection which borrows heavily from the design of the original. However, the new watches also added some subtle updates, and also moved over to a stainless steel case.  

Currently, the Samurai collection has 4 variants including a blue dial/blue bezel, a black dial/black bezel, a blue dial with a “Pepsi” bezel, and a striking gold-on-black design.


Looks sharp and wears well. Source: Watch Review Blog


The SRPB51 has a great black and gray theme, and will do just about anything you need (except fit under most shirt cuffs). 

It has a more angular case design than the popular SKX line of dive watches. Instead of the ridge pattern seen on most Seiko divers, its crown uses a very attractive and technical-looking diamond texture pattern.

As a part of Seiko’s PROSPEX line, the SRPB51 also uses 4R35 automatic movement with a 41-hour power reserve in addition to the watch hacking. Its water resistance is also 200m - which will keep the water out in most cases. 

Since the Samurai line is a bit on the more expensive side of watches, you may want to consider using this Samurai-SKX conversion case that has the sharp, good looks of a Samurai while being compatible with all SKX007 parts. 


Your Own Vision of PROSPEX

namokiMODS has some amazing options for you when it comes to Watch mod parts for a Seiko watch - and beyond. If you love Seiko watches, all of the models on this list are probably already very familiar to you. 

In fact, you may already own one or more!

Anyone who knows Seiko watches knows that we offer some of the best SKX007 parts out there. What might not be as well known is that we actually test our SKX007 cases to 200m! So if you’re planning to create a watch that you can bring to your next beach vacation or SCUBA diving excursion, check out our cases here.

With our parts, you can take your vision for PROSPEX and create your own model from our custom made Watch spare parts, or use the Seiko spare parts we offer. When you pay for genuine Seiko OEM parts - deal with us, and get what you pay for.  

June 10, 2022 — Jeremiah A

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