Tudor Pelagos FXD and Pelagos Ultra

Two current Pelagos models.

The blue Pelagos FXD has no date and no removable strap bars. The Pelagos Ultra has a date, a titanium bracelet and five times the published water-resistance rating. Take either beyond the dry side of the dock: water, wet kit and hours outdoors are the point of these watches.

Both have titanium cases, ceramic bezel inserts, sapphire crystals and Tudor’s angular Snowflake hands. Their differences begin with what the cases are built to do. The FXD’s strap bars are machined into the case itself; the Ultra’s case incorporates a helium escape valve for saturation-diving use. Those are working decisions about strap attachment and pressure, not reasons to keep titanium clear of every scuff.^[1][2]

The FXD here is the navy-blue, time-only model developed with the Marine nationale, not the black-dial US Navy-inspired version, the GMT or the chronograph. Tudor’s current product page identifies it as M25707B/26-0001, at $5,025 in the US. The page’s address retains the shorter m25707b-0001 form.^[1]

The Ultra is M2543C1A7NU-0001, at $6,900. It comes on a titanium bracelet with a second black rubber strap in the box. These are Tudor’s suggested US retail prices, before tax; availability is a separate question for an official retailer.^[2]

From the Submariner to the Pelagos.

Tudor dates its first dive watch to 1954: the Oyster Prince Submariner reference 7922, rated to 100 metres. In 1956, the French Navy’s Groupe d’Étude et de Recherches Sous-Marines began evaluating Tudor Submariners. Tudor became an official supplier to the French Navy in 1961.^[3][4]

That relationship helps explain the blue dial and square markers. Tudor identifies the blue Submariner reference 9401, supplied to the French Navy from the 1970s into the 1980s, as an inspiration for the FXD. The Snowflake hands themselves entered Tudor’s dive-watch vocabulary in 1969.^[3][4]

The Pelagos arrived in 2012. The FXD followed in 2021, reviving the French Navy collaboration with a watch developed for underwater navigation alongside its combat swimmers. “FXD” refers to the fixed strap bars. This is a documented development relationship; it does not make every retail example a military-issued watch.^[3][8]

The blue FXD’s bidirectional bezel counts down from 60 to zero. Tudor describes paired swimmers following compass bearings for timed sections of a route, then restarting the countdown at each change of course. Use the countdown and that design choice becomes tangible: the bezel is there to mark a task, not just frame the dial. That explains why it differs from a conventional unidirectional elapsed-time dive bezel. Tudor explicitly says the blue model’s bezel does not correspond to ISO 6425:2018, because it serves that navigation brief instead.^[3]

The Ultra joined the collection in April 2025. It extends the original Pelagos’s deep-diving specification to 1,000 metres and adds METAS Master Chronometer certification. It remains in the current collection alongside the 500m Pelagos, rather than replacing it.^[2][5][9]

Start with the case and the strap.

The FXD is 42mm across and 52mm from lug to lug. Tudor’s case description gives a thickness of 12.75mm; its summary rounds that to 12.8mm. The Ultra is 43mm across and 14.5mm thick. Tudor does not publish an Ultra lug-to-lug measurement on the current product page.^[1][2]

A one-millimetre diameter difference is not the whole fit comparison. The FXD’s fixed bars extend the case’s long axis, while its one-piece strap passes beneath the watch. The Ultra is thicker and comes with a three-link titanium bracelet. Try both on the intended strap or bracelet, move your wrist and check the fit against the sleeves and wet kit you actually use. A watch that stays put through a long day matters more than a tidy diameter comparison.

The blue FXD has a 200m rating and a navigation countdown bezel. The Ultra has a 1,000m rating, a unidirectional elapsed-time bezel and a helium escape valve. The latter addresses the pressure changes involved in saturation diving; it is not a control needed for an ordinary swim.^[1][2][3]

Inside, the FXD uses the COSC-certified MT5602 with approximately 70 hours of power reserve. The Ultra’s MT5612-U is COSC- and METAS-certified, with 65 hours. METAS testing covers the complete watch’s precision, resistance to magnetic fields, water resistance and power reserve. The Ultra also adds a date at three.^[1][2]

At the listed US prices, the Ultra costs $1,875 more. Its additional depth rating, certification and bracelet are concrete differences. Choose the FXD for a no-date dial, a countdown you will turn and a pass-through strap you will wear wet. Choose the Ultra for the date, factory bracelet and deeper-rated case, then put its elapsed-time bezel to work. Neither requires its owner to be a professional diver to swim, spend a day on the water or come home with salt on the case.

The specifications, side by side in detail.

Both watches wind automatically through wrist movement. Their published reserves are measured from fully wound movements, not a guarantee of how much running time a short day’s wear adds. Both have screw-down crowns and a five-year transferable Tudor guarantee.^[1][2]

The two tables describe the current references on Tudor’s US-priced pages. The older FXD photographs retain their original launch-era identification; the current blue watch’s reference includes “/26.”

Where they sit in the collection.

The Pelagos 39, M25407N-0001, is the smaller bracelet option: a 39mm grade 2 titanium case, 11.8mm thickness, 200m water resistance and a COSC-certified MT5400 with approximately 70 hours of reserve. It has 21mm lugs, a T-fit bracelet and a supplied black rubber strap. Tudor lists it at $5,625.^[6]

The standard black-dial Pelagos, M25600TN-0001, is 42mm across and 14.3mm thick, with a titanium-and-steel case, 500m rating, helium escape valve, date and COSC-certified MT5612. Its published reserve is approximately 70 hours and its current US price is $6,025. The collection also includes a blue-dial Pelagos and the Pelagos LHD, whose crown sits on the left for wearing on the right wrist.^[5][7]

Within the fixed-bar range, the black-dial FXD, M25717N-0001, is a particularly important distinction. It shares the blue FXD’s 42mm size, MT5602, 200m rating and $5,025 price, but uses a unidirectional elapsed-time bezel. Its factory fabric strap is forest green with a red central thread, and its additional rubber strap is black. It is not simply the blue watch in a different colour.^[10]

The current FXD collection also lists the FXD GMT, a 42mm titanium model at $5,475, and the FXD Chrono Cycling Edition, a 43mm black carbon-composite chronograph at $6,375. Those add different functions and different intended uses; their specifications should not be borrowed for the time-only blue FXD.^[11]

Choose among them by the work on your wrist: a countdown or elapsed time, date or no date, and the strap or bracelet that stays comfortable in the water and out. The depth figure alone says little about handling a bezel with wet hands or wearing the watch through a full day on the coast.

Both say 22 mm. They attach differently.

The FXD’s bars are part of the case. There are no removable spring bars to release a conventional two-piece strap. A replacement must thread through the fixed-bar openings, with suitable width, thickness, length and fastening. “22mm” by itself is not a compatibility guarantee.

The supplied navy fabric strap has a grey central thread, a titanium D-buckle and a self-gripping closure. Tudor developed its construction with Julien Faure, the French ribbon maker. The additional navy rubber strap is also one piece, with an embossed woven motif and titanium buckle. Both are intended for the FXD’s attachment system. Put the fabric and rubber into regular rotation on the water; neither needs to stay dry just to look new. Check the fastening and fit before heading in.^[1][3]

That fabric strap draws on a practical part of the Navy connection. Tudor records supplying historical watches without bracelets, after which sailors fitted their own straps, including examples made from parachute elastic. The modern FXD strap is a factory-made construction, not a claim that the retail watch carries an improvised military strap.^[3]

The Ultra is supplied with a satin-brushed titanium three-link bracelet. Its T-fit folding clasp includes a safety catch, a diver’s extension and a visual adjustment indicator with a luminous marker. The additional black rubber strap uses titanium end links and a titanium pin buckle; its extra extension piece can add up to 110mm.^[2][4]

Tudor lists 22mm lugs for the Ultra, but the end-link interface matters as well as the width. For replacement rubber, bracelet parts or a different strap, confirm Ultra-specific fit and the required hardware with Tudor or the strap maker. The factory straps are the documented options here; no general-purpose quick-release strap is presented as an FXD replacement.

Find the blue FXD and the Ultra.

Start with Tudor’s product pages and an official retailer. Confirm the complete reference, included straps, warranty terms and the particular watch’s availability. The blue FXD’s year-marked reference makes that last check especially useful.