Here Is Why Citizen
Makes Great Divers

The Story

The Citizen Diving Story

When Citizen released the Parawater in 1959, it was Japan’s first water-resistant wristwatch. Sealed with O-ring gaskets at the case, crystal, crown, and back, it was tested by tying watches to ocean buoys and dropping them into the Pacific to drift across the ocean. When the buoys were recovered — sometimes a year later, sometimes washed ashore on the Oregon coast — the watches were still running. Citizen had something to build on.

Twenty-six years later came the watch that defined Citizen as a true dive brand: the Aqualand, released in 1985. It was the first quartz analog-digital diver in the world with a built-in electronic depth gauge — a sensor that read water pressure and showed depth on a digital LCD. It logged your maximum depth, warned you if you ascended too quickly, and operated to 200 metres. It was the kind of watch that needed an explanation; today, dive computers do this work, but in 1985, the Aqualand stood alone.

In 1989, Citizen consolidated everything it had been building into a single line: Promaster. The first Promaster collection launched with three watches — the Aqualand for the sea, the Altichron for the mountains, the Skyhawk for the sky. The marine line evolved fast. The NY004 launched in 1993, gained a cult following, and was famously adopted by the Italian Navy’s Special Forces in 1997.

That same series — known to collectors as the Fugu, named after the spiny pufferfish whose silhouette the bezel resembles — is still in production today. The Aqualand is also still in the catalogue, mostly unchanged across nearly forty years. Few dive watches can claim that kind of continuity.

Today’s Promaster line spans accessible mechanical divers under €300 to professional 1000-metre saturation models. Solar-powered Eco-Drive sits alongside automatic and analog-digital. Some are ISO 6425 certified — actually tested, not just claimed. The collection is the technological pinnacle of Citizen’s offering, and the underlying story is consistent: build watches that work in the water, regardless of what the water does to them.

Family 01 — JP2000 series

The Aqualand

The watch that launched Promaster. The original 1985 Aqualand was the first analog-digital diver with an electronic depth gauge built in — a sensor at 9 o’clock that read water pressure and displayed depth on a small LCD. Maximum depth memory, ascent-rate warning, dive-time recording.

Today’s JP2000 series is a direct continuation. Same large case, same depth-meter sensor on the side, same analog hands paired with digital readouts. 200 metres water resistant. The watch you wear when you want all the data on your wrist, not on a separate dive computer.

Family 02 — NY0040

The Fugu

Named after the Japanese pufferfish — fugu (フグ) — because of the bezel. Look at the edge: alternating smooth and serrated sections, designed to give a wetsuit-gloved hand a secure grip even in cold water. Watch enthusiasts thought it looked like the spines of a pufferfish. The name stuck.

The Fugu lineage starts with the NY004 in 1993, famously issued to the Italian Navy’s Special Forces in 1997. The current NY0040-09E is a direct evolution. Automatic mechanical movement, ISO 6425 certified, 200 metres, 44 mm. Crown at 8 o’clock — set off-axis so it doesn’t dig into the back of the wrist. Pufferfish engraved on the case back.

Family 03 — BJ8050 series

The Ecozilla & The Godzilla 70th

When Citizen released the BJ8050 series in 2004, the watch community immediately gave it a nickname: Ecozilla. Eco-Drive plus Godzilla — because at 48 millimetres wide and 18 millimetres thick, it’s the kind of watch that has its own gravitational field. 300 metres water resistant. Mineral crystal six millimetres thick. Cult following ever since.

In 2024, Godzilla turned seventy. Citizen marked the anniversary with two limited editions on the Ecozilla case — the BJ8059-03Z (red, with a roaring Godzilla face on the dial) and the BJ8056-01E (black, with a Godzilla silhouette). Both sit alongside the standard BJ8055-04E in our stock.

If you want a watch that announces itself before you do, this is the family.

Citizen’s 36.5 mm Promaster Marine — EO2023-00W

Proper Divers, Properly Sized for women – The EO SERIES

The EO line is Citizen’s compact Promaster Marine — built to the same standard as the brand’s full-size divers, in a 36.5 mm case.

The “DIVER’S 200m” mark on the dial isn’t decorative. It signals that the watch meets ISO 6425, the international standard for diving watches: tested water resistance to 125% of rated depth, salt water exposure, magnetic and shock resistance, a unidirectional rotating bezel with elapsed-time markings, a screw-locked crown, and luminous indexes legible at 25 cm in darkness. Inside is Caliber E168 Eco-Drive — Citizen’s solar-powered movement, charged by any light source, with a six-month power reserve from full and a shock detection function built in. Class 1 antimagnetic resistance per JIS / ISO 1413 is part of the spec.

The smaller case isn’t a styling choice. On a slimmer wrist, a 44 mm diver shifts under a wetsuit cuff and can be hard to read at the angle you need it for. 36.5 mm sits flat, reads cleanly, and lets the bezel do its job the way it was designed to.

Several EO models launch as “pair” sets alongside a larger men’s counterpart — the EO2023-00W and BN0167-09W, released together in April 2026, are the latest — but each is a complete, certified diver on its own.

More women dive today than at any point in the sport’s history. The EO line is there for it.

Specs:
– 36.5 mm stainless steel case
– 200 m water resistance, ISO 6425 “DIVER’S” marked
– Class 1 antimagnetic (JIS / ISO 1413)
– Unidirectional rotating dive bezel
– Screw-locked crown, offset at 4 o’clock
– Luminous hands and indexes
– Caliber E168 Eco-Drive solar movement
– Approx. 6-month power reserve from full charge
– ±15 seconds per month accuracy
– Shock detection function

FOR DIVERS BEYOND SUNLIGHT — BN7020-09E

The Abyss Diver

Sunlight disappears in the ocean around 200 metres down. Below that is the aphotic zone — permanent darkness. At 1000 metres, the pressure is 100 atmospheres. The water is near-freezing. Nothing about the environment is survivable for a human without serious engineering around them.

The BN7020-09E is built for that world.

Citizen released it in 2017 as the world’s first solar-powered dive watch rated for 1000-metre saturation diving. That claim contains an obvious irony: a watch powered by light, designed for a depth where light doesn’t exist. But Eco-Drive doesn’t need sunlight — it charges from any light source. The watch charges on the surface or under artificial light, stores that energy for approximately 1.5 years, and runs on it long after the light is gone. The power reserve indicator on the dial tells you how much stored energy remains — which matters when your watch won’t see daylight for weeks.

The case is Super Titanium — Citizen’s proprietary titanium treated with Duratect MRK surface hardening and a DLC (diamond-like carbon) coating. The result is a case roughly 40% lighter than stainless steel, significantly harder than untreated titanium, and resistant to scratching at a level most dive watches can’t match. At 100 bar of pressure, material choices stop being cosmetic.

The bezel has its own engineering. Most dive bezels use friction or click systems — you rotate them, they stay. The BN7020-09E adds a twist-to-lock mechanism: a visible ring around the bezel that physically locks it in position when turned clockwise. Underwater, at depth, with gloves, an accidental bezel shift could misrepresent elapsed time. The lock removes that possibility.

Like the BN1024, the BN7020-09E carries a helium escape valve — this one at 10 o’clock — and is ISO 6425 compliant for saturation diving. It was tested in a helium-oxygen pressure chamber for 15 days and then subjected to high-speed decompression. At 52.5 mm across and roughly 22 mm thick, it’s a large watch. That size is the engineering envelope required to survive 100 bar.

Specs:

– Helium escape valve at 10 o’clock
– ISO 6425 compliant for saturation diving
– 1000 metres water resistance
– Sapphire crystal with anti-reflective coating
– Caliber J210 Eco-Drive — approximately 1.5 years (540 days) power reserve on full charge
– Super Titanium case (Duratect DLC + MRK surface hardening)
– Black polyurethane strap with dive suit extension
– 52.5 mm diameter, ~22 mm thick, lugless case
– Screw-down crown at 4 o’clock
– Unidirectional bezel with twist-to-lock mechanism
– Power reserve indicator
– Natulite luminous paint on hands, markers, and bezel pip
– Released 2017

For divers beyond deep — BN1024-01Z & BN1024-01E

The Saturation Diver

Most dive watches are designed for recreational diving — snorkeling, scuba to 40 metres, swimming pools, beaches. They’re rated for situations where the human body can also survive. They’re excellent at what they do.

The BN1024 pair is built for what’s beyond that.

Saturation diving is what professional commercial divers do — extended deep-water work, often on offshore oil platforms or in marine engineering. They live in pressurized habitats for days at a time, breathing a helium-oxygen mix to prevent nitrogen narcosis at depth. Then they decompress slowly, sometimes over days, to return safely to surface pressure.

The problem with regular dive watches in that environment: helium atoms are tiny enough to seep into the watch case at high pressure. When the diver decompresses, the trapped helium inside the watch expands faster than it can escape through normal seals — fast enough to pop the crystal clean off the case.

A saturation-grade dive watch solves this with a helium escape valve. The BN1024 has one at 2 o’clock. It opens during decompression and gives the trapped gas a controlled release path before pressure builds.

That feature is why the BN1024 is also ISO 6425 Annex A certified — the additional set of ISO 6425 requirements specifically for saturation diving watches, on top of the standard ISO 6425 certification. Many fewer dive watches meet it.

Most owners will never saturation dive. Wearing the BN1024 isn’t really about that. It’s about wearing the version of a tool that’s fully built to do its real job — the way a professional camera’s burst mode is over-engineered for someone shooting holiday photos. The capability is the point. Released April 2025, this is Citizen’s newest professional diver, and one of very few watches at this price that’s properly built for the job.

Specs:

– Helium escape valve at 2 o’clock
– ISO 6425 Annex A certified (the saturation diving standard, beyond regular ISO 6425)
– 300 metres water resistance
– Sapphire crystal with anti-reflective coating
– Caliber E365 Eco-Drive — 365 days power reserve on a full charge
– BENEBiOL plant-based polyurethane strap
– 46 mm diameter, 16.3 mm thick, lugless case
– Crown at 4 o’clock with crown guard
– Two dial options: gradient black (BN1024-01E) or gradient crimson red (BN1024-01Z)
– Released April 2025

One watch for two environments — BN4021-02E

The Altichron

The Altichron is not a Divers’ watch, but it deserves a spot on the page because they are watches the “Go Beyond”.

The original 1989 Altichron was one of the three watches that launched the entire Promaster line. It was the world’s first electronic wristwatch with a built-in altimeter — designed for climbers, with a pressure sensor that read altitude from -300 metres up to over 5,000 metres above sea level.

That heritage is rare. Few watches can claim a “world’s first” technical breakthrough; even fewer have kept the idea in production for nearly forty years.

The current BN4021-02E carries the Altichron forward and adds something the original didn’t have: a true 200m dive-rated case. So you’ve now got an altimeter, a digital compass, a calibration function, AND real saltwater protection — all wrapped in Super Titanium, all powered by Eco-Drive solar.

This is the watch you wear when you’re not sure where your day will end up. Trail in the morning, beach in the afternoon, no need to switch wrists.

Specs:

– Altimeter from -300 metres to over 5,000 metres
– Digital compass with calibration function
– 200 metres water resistance
– Super Titanium case — hypoallergenic, lighter than steel
– 49.5 mm diameter
– Eco-Drive solar with 11-month power reserve
– Citizen Caliber J280
– Mineral crystal with anti-reflective treatment

for real divers

The ISO 6425 Certified

Many dive watches list “200 m water resistant.” Far fewer have actually been tested by an independent process and certified to ISO 6425. Multiple Citizen Promasters have. They’re verified for water resistance, magnetic resistance, shock resistance, chemical (saltwater) resistance, strap solidity, and time-zone reliability — the full ISO battery for diver’s watches.
From 200 to 300 metres of depth rating. Mechanical, solar, and analog-digital. You’ll spot them by the word “DIVER’S” on the dial — that apostrophe-s is the ISO 6425 signature, reserved for watches that pass.

Not every diver needs to be a 48 mm tool watch. The most-worn Citizen divers in most collections are the everyday ones — Eco-Drive solar, 200 m water resistance, 40-something millimetres on the wrist, ready for swimming pools, beaches, rain, and life in general. These are the ones you put on in the morning and forget about. No battery to swap. No winding. No fuss. Just light.

For those who prefer the feel of a mechanical movement, the NY-series automatic divers are descendants of the same NY004 platform that birthed the Fugu — different colorways, different finishings, same proven case.