Naomi Uemura is an adventurer with a dazzling array of accomplishments, including the first person to climb the highest peaks on all five continents, a 12,000km solo dog sled across the Arctic Circle, and a 3000km crossing of Greenland. It's well-known that on his adventures he carried a 1970 model of the Seiko Second Diver, a diver's watch released by Seiko in 1968. However, there are no records that reveal which Second Diver he was taken on, or which 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 (ZENMAI WORKS)
[Article published on January 17, 2026]
What is a “second diver”?
Seiko's "Seiko Diver 61MC" (6105-8000, 6105-8110 from 1970). Commonly known as the "Seiko Second Diver" (hereafter referred to as "Second Diver"), this is an old diver's watch that Seiko manufactured from 1968 to 1976.
The reason why this watch is called the "Second Diver" by enthusiasts is likely because the first diver's watch released by Seiko in 1965, the 6217-8000/8001, was called the "First Diver."
This diver's watch was released by Seiko in 1965. Although it does not have a screw-down crown, it is water resistant to 150m. This model was also donated as equipment to wintering members of the Antarctic Research Expedition from 1966.
Incidentally, in 1967, the year before the birth of the Second Diver, Seiko released the 6215-7000 (later evolved into the 6159-7001). However, this model was a professional diver's watch boasting a water resistance of 300m at the time. In other words, it was a high-end model, so it is thought that the 6105-8110, which was equipped with a Cal. 61-type movement and was water resistant to 150m, was given the name "Second" among fans.
So, in this article, I will refer to 6105-8110 as the second diver.
From meeting Naomi Uemura to the adventures surrounding "Uemura Diver"
I got my hands on this Second Diver in 2019 and have been using it for about seven years. Like many enthusiasts, I began to look into the history of this watch with great enthusiasm, and it was there that I came across a rare adventurer named Naomi Uemura.
*In the lecture notes, Uemura Naomi gently denies being called an "adventurer." The real reason is that adventure is an act of "taking risks." He always considered it best to avoid risk in his activities and return alive. Therefore, "explorer" might be a more appropriate term. In the first place, Uemura may not need a title, but for convenience, I will use the most common term, "adventurer."
Born in Hyogo Prefecture in 1941, he worked for a transportation company after graduating from high school and then enrolled in the Faculty of Agriculture at Meiji University. He has solo climbed Europe's highest peak, Mont Blanc, and Africa's highest peak, Mount Kilimanjaro. In 1970, he joined the Japan Alpine Club's Everest climbing team, and in May of that year, together with team member Teruo Matsuura, he became the first Japanese to successfully reach the summit of Everest (the watch donated by Seiko to the Japan Alpine Club's Everest climbing team at the time was the 6159-7001). The following year, he solo climbed North America's highest peak, Mount McKinley (Denali), becoming the first person in the world to climb the highest peaks on five continents. Between 1974 and 1976, he traveled 12,000 km solo by dog sled across the Arctic Circle, reached the North Pole alone in 1978, and also traveled 3000 km across Greenland. However, after successfully summiting Mount McKinley alone in the dead of winter in 1984, he disappeared on the way down. In the same year, he was awarded the People's Honor Award.
For me, born in 1971, the name Naomi Uemura has a special ring to it.
In 1984, Naoki Uemura became the first person in the world to climb Mount McKinley, North America's highest peak, alone in the dead of winter, but was lost on the way down the mountain and never returned. I was a child and saw the news in real time, and his name was engraved in my memory.
To be honest, I didn't have much interest in it after that, and I had almost forgotten its name, but when I got my hands on a Seiko Second Diver and learned about the journey this watch had taken with him, I wanted to learn more about him. For example, if you get an Omega Speedmaster, you might become interested in NASA and space, even if you hadn't had much interest before. Historic watches have the power to give adults a chance to relive their childhood. They want to use watches as a medium to enhance their knowledge, culture, and intellectual curiosity.
Returning to the topic at hand, this Second Diver is the very watch that world-famous adventurer Naomi Uemura used on his Arctic adventure. That's why the nickname "Uemura Diver" is so popular among Japanese fans. However, the more I researched it, the more I realized that the history surrounding this watch and Naomi Uemura continues to circulate around the world with extremely vague and confusing information.
What surprised me most was that there was no description that answered the most important question: "On what adventure did Naoki Uemura wear this watch?" Furthermore, the question of "Was the model he was wearing then a mid- or late-period model?" remains unclear.
Furthermore, the specifications for the Second Diver were not well organized.
That's why I've always wanted to properly organize the history and structure of the "6105-8110." And now, the editorial team at "webChronos," the online publication of the watch magazine "Chronos Japan," has given me that opportunity. They even gave me the opportunity to interview Seiko Watch, the creator of the Second Diver.
So, first of all, I would like to express my gratitude to the Kronos editorial department.
From here on, I would like to embark on an adventure with you all on the "Seiko Second Diver" adventure.
A complicated history
It is an undeniable fact that Naomi Uemura wore the Second Diver, also known as the 6105-8110, on his wrist during his Arctic adventures. While there is no mention of Seiko diver's watches in the books and magazines published by Bungeishunju at the time, there are several photographs of a watch that appears to be the Second Diver on Naomi Uemura's wrist.
Seiko Watches themselves have stated this clearly on their official website. When they released the Seiko Prospex "Diver Scuba 1970 Mechanical Diver Reissue" Ref. SBDX031, which is a reissue model of the Second Diver design, they explained that he carried the Second Diver with him on his "solo dog sled journey of 12,000 km across the Arctic Circle" from 1974 to 1976.
*Reproduction design model: Rather than a complete reproduction of the original, this model is a reproduction of the design while still meeting the requirements of modern diver's watches. For example, the Ref. SBDX031 is equipped with the Cal. 8L35 movement, which is made exclusively for diver's watches at the Shizukuishi High-End Watch Workshop in Shizukuishi, Iwate Prefecture, which has been assembling high-end mechanical watches since 2004. The case is also Zaratsu polished, and its water resistance has been increased from the original's 150m to 200m for air diving, making it a much higher quality model compared to the original.
Automatic movement (Cal. 8L35). 26 jewels. 28,800 vph. Power reserve approximately 50 hours. Stainless steel case (diameter 45.0 mm, thickness 13.0 mm). 200m water resistant for air diving. Limited to 2500 pieces worldwide. Discontinued.
こういった事実があるにもかかわらず、ちまたでは植村ダイバーの情報が錯綜している。端的に言えば1974～1976年にかけて行われた「北極圏1万2000km犬ぞり単独行」と、その後1978年3月5日～4月29日にかけて行われた「北極点単独行」、さらには続けて行われた1978年5月12日～8月22日の「グリーンランド縦断」を、混同しているケースが多々見受けられるのだ。
Furthermore, the story of the solo North Pole expedition is a complicated one. Actually, it would be rude to call it complicated; it's a romantic story.
As mentioned above, Naomi Uemura wore a Rolex during his adventure to the North Pole in 1978. It was a gift from Rolex Japan to support his adventure.
However, midway through the adventure, the Rolex stopped working. Feeling sympathy for the supply plane, Naomi Uemura exchanged his watch with a Bungeishunju journalist (Atsuo Shitara) who was covering the mission, and the pilot safely completed the remainder of the adventure. Legend has it that the watch he exchanged with was made by Seiko. Furthermore, this watch is often confused with a second diver's watch.
However, there is not a single document that states that this was a second diver.
Incidentally, it is said that the Rolex that Naomi Uemura wore at the time was an Explorer II. It certainly was the perfect watch for the legendary explorer Naomi Uemura. Functionally, the Explorer II, with its 24-hour bezel and hands, was also the perfect choice for the midnight sun of the Arctic.
Also, considering the timing, the "solo expedition to the North Pole" is said to have departed from Cape Columbia, the northernmost point in Canada, on March 5, 1978, so it can be assumed that the model is the first model of the Explorer II, "Ref. 1655," which was sold from around 1971 to 1984.
If you browse the internet, you'll find a number of articles and blogs detailing this story as if it were true. One web article featuring a second diver from overseas even includes a page from a Japanese magazine that mentions an Explorer II as part of their equipment. (At first, the magazine in question was unknown, but later, an interview with Uemura Adventure Center revealed which magazine it was. Stay tuned for more!)
Incidentally, the replaced Rolex is said to have started working again once Shitara put it on his wrist. At the time, Naomi Uemura was wearing a leather strap on his Explorer II. The strap broke during the journey, so he attached it to his waist by a string, and it stopped. The reason the watch stopped was probably because it was exposed to the outside air without any heat transfer, causing the oil to solidify. If we believe the story that it worked fine once Shitara put it on, it seems unlikely that it was broken by the vibrations of the sled or something.
The Explorer II Ref. 1655 was released in 1971. While the current model has a separate hour hand, the first model had a function that linked it to the hour hand. Rolex watches are also beloved by many adventurers and are known to have been taken on their adventures.
It is said that Naomi Uemura used a leather strap to avoid frostbite. Incidentally, during his "12,000km Dog Sled" adventure, he used a stainless steel bracelet for his second diver. He probably didn't use a rubber strap because the resins available at the time couldn't withstand the cold, and so his leather strap for the North Pole adventure was likely a further improvement.
Returning to the point, there is no official record that the Seiko watch exchanged with Shitara during the solo expedition to the North Pole was a Second Diver. If Shitara had been a regular user of a Second Diver, the story would be different, but if that were the case, there would have been a lot of buzz, with people saying, "Once again, a Seiko Second Diver saved Naoki Uemura!" In other words, this episode is imbued with a somewhat forced sense of drama, as if "Seiko beat Rolex in extreme conditions."
Unfortunately, Shitara Atsuo has already passed away, so there is no longer a chance to hear this story directly from him. However, his family may have passed on the story to us.
Incidentally, the watches (and equipment) used in the "North Pole and Greenland Adventure" have been listed in several publications.
The list of watches listed in "Naomi Uemura: Everything About Adventure" (1978, Bungeishunju Deluxe) (1974-1979, Bungeishunju) includes Chopard, Casio MQ-1, and Seiko quartz watches. Also published by Bungeishunju, the hardcover "Naomi Uemura: Solo Journey to the North Pole and Greenland" (1978) lists Chopard and Seiko digital and quartz watches, as well as the word "Rolex" and "Oyster" at the end of the book.
Was the "12,000km Dog Sled" the only adventure in which Uemura Naomi actually wore a second diver?
I was determined to get closer to the truth, and the Chronos editorial team gave me a great opportunity. I was given the opportunity to visit Seiko Watch headquarters and interview them about the "6105-8110." (Continued in Part 2)
