Naomi Uemura is an adventurer with brilliant achievements, including the first person to climb the highest peaks on all five continents, traveling 12,000km solo by dog sled across the Arctic Circle, and traversing Greenland 3000km. It's well-known that on his adventures he carried a diver's watch, commonly known as the "Seiko Second Diver," released by Seiko in 1968. However, there are no records that reveal which Second Diver he was taken on, or what model it was, and various anecdotes are circulating. To find out, motor journalist and self-confessed Second Diver enthusiast Hiroki Yamada conducted an original investigation. This is the story of the adventures of "Uemura Diver."
Text by Kouki Yamada
Special thanks to Tsutomu Sato (ZENMAIWORKS)
[Article published on January 23, 2026]
Interview with Seiko Watch Headquarters: Naoki Uemura and the Second Diver
The Seiko Diver 61MC (6105-8000, 6105-8110 from 1970), commonly known as the "Seiko Second Diver" (hereafter "Second Diver"), was released in 1968 and loved by many adventurers for its toughness. It is well-known that Naomi Uemura took this diver's watch with him on his solo dog sled journey of 12,000 km across the Arctic Circle, and the watch came to be known as the "Uemura Diver."
However, this legend has been passed down vaguely, with some inaccurate information mixed in.
This is because, in addition to his solo 12,000km journey across the Arctic Circle, which began in 1974 and took about a year and a half, Uemura also completed two other adventures: a solo journey to the North Pole and a traverse of Greenland in 1978. Furthermore, accounts of the use of second divers on these adventures have been spreading as if they were factual accounts on the Internet.
So, on what adventure did Naomi Uemura don the Second Diver gear?
And what model was he wearing at the time? Was it an early, mid or late model Second Diver?
To answer this extremely simple question, I embarked on an "adventure with Uemura Diver" with the cooperation of the editorial team at webChronos, the online publication of the watch magazine Chronos Japan.
Our destination was Ginza 1-Chome, the headquarters of Seiko Watch, located in the heart of Tokyo.
Seiko Watch Corporation is located in Ginza, Chuo-ku, Tokyo.
Before the interview, about the encounter between the author and the second diver
Before heading to Seiko for my interview, I would like to talk a little about my encounter with Second Diver.
I first got my hands on the Second Diver in the winter of 2019, about six years ago.
In other words, from the perspective of "real" people, I was probably quite late in becoming interested in the Second Diver. At the time, phrases like "Back in the day, (Second Divers) cost less than 10 yen" were flying around the internet in the old Seiko community, and when I thought about the time when it was possible to purchase a good-quality example for a price much lower than when I purchased it in 2019, I sighed and realized how late I was in realizing its appeal.
The reason I was attracted to Second Diver was simply because of its appearance.
Actually, at first I thought, "What a strange design."
At the time, I knew absolutely nothing about watches, and the chunky, asymmetrical case looked quite odd to me.
I had always thought that diver's watches had round hour markers, so the square hour markers on the second diver's watch with their thick borders were intimidating in a good way.
The minute markers, marked with silver lines, were truly unadorned, with no Arabic numerals at all, and everything was expressed with squares and lines.The dial was matte, with no reflections, and I intuitively felt that this was a watch that was an instrument.
The crystal on my watch was not the original, but a flat aftermarket product that was released when the Second Diver was being manufactured. The original crystal was raised in three dimensions, so when the dial was viewed from an angle, the minute markers and long hand were bent (even this appearance is a charm point for enthusiasts). Also, because the crystal surface protruded, it had a reputation for being easily scratched. In contrast, my crystal was less distinctive, but the dial was easier to read. Both crystals were made of mineral glass, but the genuine Seiko product was made of "Hardlex," a material developed in-house by the company.
To accommodate this extremely cool and large dial, an even larger case was used, and the crown at 4 o'clock was designed to be pinched up, making the Second Diver very charming from a bird's-eye view. Even though the watchmaker himself behaved quite seriously, he still appeared somewhat comical, like Charles Chaplin, and that's what captivated me.
By the way, when I was young, I owned a 1968 Alfa Romeo GT1300Jr. The design of the car, commonly known as the "Giulia Coupe," designed by Giorgetto Giugiaro during his time at Bertone, had the hood tip avoiding the body, which was why it was called "stepped." The round reflector lamps used from 1960 to 1970 were positioned closer to the center, giving it a very cute look.
The reason why watches (and cars) that are considered classic or vintage so strongly appeal to beginners and young people is probably because they evoke a sense of newness that is not found in modern times.
And old industrial products have a certain dignity. Compared to today, the technology was still in its infancy, and although cost was important, ideals were higher, so I think it was easy to create great machines and masterpieces.
I've digressed a little, but perhaps this is why I intuitively sensed the same kind of romance in this second diver that I also felt in "Julia."
We enter Seiko Watch headquarters and are shown valuable documents!
On August 26, 2025, Seiko Watch conducted an interview about Diver Uemura.
Seiko Watches and Naoki Uemura
I felt quite out of place as an outsider visiting a manufacturer that Japan is proud of around the world. Perhaps sensing my hesitation, Shotaro Hanamura of Seiko Watch's Product Planning Division 2 and Junpei Matsue of the Product Design Division, who assisted me, welcomed me with warm smiles.
However, contrary to her smile, Hanamura's first words were quite shocking.
"I know this may be disappointing at first, but the truth is that there are almost no documents related to Naomi Uemura left at Seiko Watch Headquarters."
Naturally, this left me confused. Was that the end of the story? If so, why did he agree to be interviewed?
I was impatiently waiting for him to speak, and sure enough, there was more to come.
"Very little remains, but among those few documents... I found an incredible clue!"
Hanamura-san is quite good at getting the conversation going. In fact, there was a great deal of seriousness in his voice, so I think he was probably trying to convey to the author the excitement he felt when he found this document.
The document in question was the August 1973 issue of "Seiko News," a booklet of information about new products sent by Seiko Watch Company to retailers.
"Mr. Uemura actually contributed an article about what it was like at the time to the August issue of Seiko News."
1973 was before Naomi Uemura embarked on his "12,000km solo expedition across the Arctic Circle," so does that mean that Second Diver watches were being worn before then?
As if to calm the author's excitement, Hanamura read out the article that was projected onto the screen.
"Snow and ice as far as the eye can see. No landmarks to guide me. In temperatures as low as minus 45 degrees, the only things that tell me where I am are the sun, a sextant, and my Seiko watch.
(..snip..)
How far have I come? The only clue I have to where I am is my watch. My watch (Seiko Diver 61MC) has been with me since my trip to Antarctica last February. I have absolute confidence in its performance.
Indeed, this was a contribution written after Uemura Naomi went to Greenland to train as a dog sledder in order to fulfill his dream of crossing Antarctica 3000 km alone, and completed a solo dog sled journey of approximately 3000 km round trip from Siorapark to Upanavik.
A sextant is a device that uses the angle of the rising sun to determine one's location, latitude and longitude. During his solo expedition to the North Pole in 1978, Naomi Uemura used a beacon unit that utilized NASA satellites (although it is said that this modernization of portable equipment significantly increased the cost of adventure), but until then, people relied on this sextant and a watch to determine their location. Incidentally, to check your location using a watch, hold the watch horizontally to the ground and point the hour hand toward the sun. The exact center point between the 12 o'clock marker and the watch is approximately south (in the Northern Hemisphere; this method does not work in extremely high latitude locations such as the North Pole).
Returning to the point, as this article states, Naomi Uemura was wearing his Second Diver's license during his "trip to Antarctica in February of last year," meaning February 1972.
Incidentally, "Seiko Diver 61MC (hereinafter referred to as 61MC)" is the official name of the Second Diver. That sounds arrogant, but to be honest, I wasn't even aware of the old name. 61MC literally means "Seikomatic Calendar equipped with a Cal. 61 series movement."
If this is the case, then if this 61MC (let's call it that from now on) was not Uemura Naoki's personal watch, but was provided by Seiko, then he would have received a new one, which would make it highly likely that the watch was at least "manufactured between 1970 and January 1972."
As if waiting for my guess, Hanamura continued:
"Then, in a certain book, I found a passage that hinted at 'that'!"
"That" is the fact that Uemura Naomi's 61MC was indeed supplied by Seiko. The passage about this is a section in "Uemura Naomi's Adventure Trail" (2020, a revised version of "Uemura Naomi's Adventure Trail: Acorn Runs Through the Earth," which was serialized in "Yama to Keikokusha" in 1977) published by Yamakei Bunko (now Yama to Keikokusha). There is a description of his visit to Antarctica,
Among the luggage weighing over 80 kilograms, I also brought books about mountains, a camera, film, and a watch.
"The practice of bribing government officials is not limited to Japan.
(..snip..)
The "bribe" watches and cameras were given to him by private companies."
Was written.
Furthermore, in the text
In reality, I was given permission to board the ship and go to the base with just a watch and a camera as souvenirs.
There was also a description that said:
This raises the question of what kind of watch Naomi Uemura gave to the official as a bribe. However, it turns out that he had been using the 61MC provided by Seiko since before he left for Argentina.
So when did Naomi Uemura get his second diver?
While we're at it, I'd like to dig deeper into when Naoki Uemura acquired the 61MC.
On page 216 of "Naomi Uemura's Adventures," it says:
Just a week after returning from my journey across Japan, I found myself standing in the crowded lobby of Haneda Airport.
"This Crossing of Japan" refers to a 50-day walking pilgrimage undertaken by Naomi Uemura from August 30 to October 20, 1971. By walking 3000 km from Wakkanai in Hokkaido to Kagoshima in Kyushu, he aimed to impress upon himself the scale of crossing Antarctica. Incidentally, the journey has been featured in books and magazines published by Bungeishunju. However, as far as I can see, there are many truly unfortunate photographs, but I was unable to determine whether the watch on the left wrist was a 61MC.
If Seiko handed over the 61MC to him before he embarked on this journey across Japan, it would have been before August 30, 1971. If it was handed over to him after the journey was over, it would have been after October 20, 1971. Either way, it's highly likely that Seiko handed over the 61MC to him in 1971.
In other words, the model that corresponds to the "Uemura Diver" is...
This allowed us to determine when Naomi Uemura acquired his 61MC. At the same time, we were also able to identify the model. It was a mid-model made in 1971.
As enthusiasts know, the 61MC underwent several specification changes during its sales period from 1968 to 1976. These changes can be broadly divided into the "early model" (1968-1970) with a simple "C-shaped" case and the Caliber 6105A movement without a hack (seconds hand stop) function, and the "late model" with a crown guard due to the unique crown lock mechanism. From an enthusiast's perspective, this later model can be further divided into the "mid-model" and "late model" based on the design of the case back.
The case back of the mid-model has the same horseshoe mark as the early model, but from around 1974 this was changed to a simpler design.
To go into more detail, only the mid-model released around 1970 has the same design as the early model, with the inscription "150m" (with a lowercase m) and "PROOF" on the dial and "WATERPROOF" (in continuous letters) on the case back.
Then, for the mid-model produced from around 1970 to around 1974, the inscription on the dial changed to "150M" (with a capital M) and "RESIST," and the inscription on the case back changed to "RESISTANT."
However, the initial model of the mid-model (?) was only produced for one year, so the mid-model that people are talking about generally refers to the "Big M" model after the minor change.
A sensational conclusion
Finally, Hanamura uttered the most sensational comment of the interview.
"The conclusion is that the model that Uemura-san was using was made in 1971. This is from the Uemura Adventure Museum (https://www.uemura-museum-tokyo.jp/) and checked the actual condition and specifications of the item, which is how we came to this conclusion."
That is.
I see... I should have visited the Uemura Adventure Museum!
This was a blind spot for me as well. Of course, I had looked at the Uemura Adventure Museum's website and checked the blogs of people who had visited the museum. However, I could not find any mention or photos of the "61MC." I even read a blog that said, "There was no exhibit featuring the Uemura diver."
However, there must be some reason why the Uemura Adventure Museum has not exhibited the 61MC until now (please look forward to the sequel). Also, as these vintage items become more valuable with each passing year, there is a risk that they may be stolen by being exhibited, or that counterfeits may be made by taking photographs of them.
So, readers who love the 61MC and watches, please refrain from contacting Uemura Adventure Museum with any inquiries regarding watches.
But even so, adventure is all about using your own two feet. I felt ashamed of myself for not going back to basics and instead criticizing the information on the internet, only to be led astray by it.
Also, if the author had inquired at the Adventure Museum and easily found out the age of the model used by Naomi Uemura, this history would never have been revealed.
In response to my request, Mr. Hanamura thoroughly researched the 61MC and Naomi Uemura's internal materials within Seiko, and then contacted the Uemura Adventure Museum for final confirmation, which is why this adventure can be said to have been completed.
Ultimately, the adventure isn't over yet
In this adventure, we were finally able to identify the model used by Naomi Uemura. However, if you dig into the details (that's what mania and geeks are all about), it's true that there are still many unclear points about the adventures of the Uemura diver.
For example, whether he carried this watch on any adventures after his inspection tour from South America to Antarctica, his life in Siorapark, or his "3000 km dog sled" and "12,000 km solo dog sled journey" remains a mystery.
The author has no evidence to support the commonly circulated anecdote that a Rolex was exchanged for a Seiko during a solo expedition to the North Pole.
There are some stories online that the watch he wore during his final attempt at McKinley in winter was not a Seiko, but there are no official books or documents to support this.
This is just my personal guess, but I think Naomi Uemura probably didn't wear the 61MC on his subsequent adventures.
Of course, the fact that this watch still exists is proof that Uemura Naomi continued to use the 61MC after that, or that he continued to keep it as a memento of that experience. However, his subsequent adventures required more extensive equipment and support systems, which required enormous amounts of funding, and Uemura Naomi would have worn a variety of the latest watches to secure this support.
According to "Naomi Uemura: Everything About Adventure" (1978), published by Bungeishunju Deluxe, the list of items carried by Uemura on his solo expedition to the North Pole in 1978 includes the names "Chopard" and "Seiko Quartz." On the other hand, even if he may have carried the 61MC as a personal watch, the name 61MC does not appear on the official list.
As I have said many times, this is just my speculation, so if anyone has information on whether 61MC was used in other adventures, please contact the Kronos editorial department.
However, it is a fact that in 1971, Naomi Uemura wore and loved the 61MC, ultimately completing a solo 12,000km trek across the Arctic Circle, and that the model he wore on that occasion was a mid-life minor change model also manufactured in 1971. Just knowing this makes me extremely happy.
I would also like to express my gratitude to everyone at Seiko Watch who followed in my footsteps, and to the Chronos editorial team who helped make this adventure possible.
In my next post, I will delve deeper into the questions I had about the 61MC itself.
