Best Straps for the Longines HydroConquest

At a Glance

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The Longines HydroConquest is one of the best-value dive watches you can buy. Full stop. At 300 metres water resistance with a ceramic bezel insert, a reliable automatic movement with 72 hours of power reserve, and the kind of build quality that punches well above its price point, it competes with watches that cost two or three times as much. The 41mm case hits a sweet spot that works on almost any wrist, and whether you've opted for the black or blue dial, the HydroConquest has a confident, purposeful presence that says "real dive watch" rather than "desk diver."

Here's what most HydroConquest owners discover pretty quickly: the watch comes on a bracelet, and while the bracelet is perfectly good, taking it off and putting the watch on a strap completely transforms the experience. The HydroConquest on rubber feels like a different watch — lighter, sportier, and more comfortable in warm weather. On leather, it goes from tool watch to smart casual in seconds. The 21mm lug width is slightly unconventional, but Delugs offers every strap in odd sizes, so compatibility is never an issue.

I've been rotating straps on the HydroConquest for a while now, and these are my 7 picks — each one chosen to bring out a different side of this incredibly versatile dive watch.

Quick Specs

The HydroConquest uses a 21mm lug width — slightly unconventional compared to the more common 20mm or 22mm, but this is never a problem with Delugs since every strap is available in 21mm. The 300m water resistance means this is a genuinely capable dive watch, and your strap choices should reflect that: rubber is the most natural material for a watch that's built for the water, but leather and sailcloth options work exceptionally well for land-based wear.

Colour-wise, the HydroConquest's most popular configurations are the black and blue dials. Black is the chameleon — it works with virtually any strap colour. Blue opens up beautiful tonal pairing opportunities with navy straps. Both dial colours respond well to monochromatic pairings (matching the strap to the dial) as well as contrast plays (black strap on blue dial, or vice versa).

Already know what you're looking for? Browse all HydroConquest-compatible straps on the Strap Finder →

Best Overall — Black CTS Rubber (Plain)

A 300-metre dive watch belongs on rubber. It's that simple.

The Black CTS Rubber Strap is the most logical first strap for any HydroConquest owner. Made from FKM fluoroelastomer — the same compound used in high-performance automotive seals — it's completely waterproof, UV-resistant, and impervious to sweat, sunscreen, and salt water. On a dive watch rated to 300 metres, having a strap that can match that water capability isn't a luxury; it's the right choice for the intended purpose.

The CTS (Cut-To-Size) design is a game-changer if you've never tried it. You trim the strap to your exact wrist measurement with a pair of scissors, so there's no leftover tail or strap keepers to deal with. The included deployant clasp has micro-adjustment positions on each side for fine-tuning the fit throughout the day — particularly useful when your wrist swells in warm weather or after exercise. At 3.3mm thick, the strap has enough substance to balance the HydroConquest's 41mm case without adding unnecessary bulk.

Black rubber on the HydroConquest — whether you have the black or blue dial — is the definition of a do-everything combination. Pool, beach, office, dinner. No break-in, no maintenance, no second thoughts. This is where you start.

Other CTS Rubber colours worth considering:

• Navy CTS Rubber (Plain) — exceptional tonal match with the blue-dial HydroConquest; creates a seamless, monochromatic look

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Dressy — Black Alligator Signature (Matte)

Alligator on a dive watch sounds like a contradiction — until you see it in person.

The Black Matte Alligator Signature Strap uses skins sourced from Haas, one of France's most prestigious exotic tanneries. The matte finish is key — a glossy alligator would clash with the HydroConquest's sport-watch DNA, but matte reads as textured and understated. The natural scale pattern adds visual sophistication without demanding attention, and the black colour ensures the strap integrates seamlessly with either the black or blue dial.

The Signature profile (4.5mm tapering to 2.2mm) gives the 41mm case serious presence on the wrist. There's a visual weight to the padded construction that transforms the HydroConquest from a dive tool into something that can anchor a dark suit or a blazer. The saddle stitching adds a handcrafted detail that steel and rubber simply can't replicate. This is the strap for the occasions where you want to wear your favourite watch but the bracelet feels too casual — weddings, dinners, client meetings.

One practical note: alligator is not water-resistant, so this is a land-only strap. Save the rubber for the pool and the alligator for the office.

Other alligator options:

• Navy Alligator Signature (Matte) — a tonal match with the blue-dial HydroConquest that's quietly stunning

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Everyday — Black Epsom Slim

If you want a leather strap that can handle the demands of daily wear without looking tired after a few weeks, Epsom is the answer.

The Black Epsom Slim Strap is produced by Haas in France. The cross-hatch grain is created by embossing calfskin under pressure, which makes the surface naturally resistant to scratches and water marks. Minor scuffs and marks tend to disappear into the pattern — exactly the quality you want in a strap you're reaching for every morning. Epsom maintains its structured, fresh appearance far longer than most unembossed leathers.

On the HydroConquest, black Epsom creates a clean, professional look that tones down the dive-watch sportiness just enough for the office. The strap absorbs into the dark dial and bezel, letting the watch's design details do the talking without any colour competition. At 2.2mm, the Slim profile dramatically reduces the wrist stack compared to the original bracelet — the HydroConquest feels lighter, leaner, and more comfortable for all-day wear. It's the kind of strap that works equally well with a dress shirt or a weekend polo.

Other Epsom colours:

• Navy Epsom Slim — a tonal match for the blue dial that adds leather refinement to the sporty case

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Minimalist — Black Saffiano Stitchless

The HydroConquest already has plenty going on visually — unidirectional bezel, date window, chunky indices, and that signature scalloped crown guard. Sometimes the best strap is one that steps back.

The Black Saffiano Stitchless Strap does exactly that. The stitchless construction removes all visual noise — no thread, no contrast details, just clean leather and precision edge paint. The Saffiano cross-hatch pattern adds subtle texture without bulk, and the black colour creates a seamless integration with the HydroConquest's dial and bezel.

Saffiano leather is produced by embossing wax over calfskin, creating a surface that's naturally resistant to scratches and light moisture. Despite looking refined, it's surprisingly tough for daily wear — the wax treatment gives it a durability that belies its elegant appearance. At 2.2mm, the Stitchless profile keeps the HydroConquest looking streamlined, and the clean edges give the watch a polished, almost dressy character that opens up smart-casual territory.

This is the strap for dinners, date nights, and work events — occasions where the bracelet feels too sporty but you still want your HydroConquest on your wrist.

Other Saffiano options:

• Navy Saffiano Stitchless — beautiful tonal pairing with the blue dial; minimalist and refined

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Sporty — Navy CTS Rubber Waffle

If the plain CTS Rubber is the practical choice, the Waffle is the one with personality.

The Navy CTS Rubber Waffle Strap takes everything that makes the standard CTS Rubber great — FKM fluoroelastomer, Cut-To-Size trimming, deployant clasp with micro-adjustment — and adds a vintage-inspired waffle texture across the surface. The recessed grid pattern isn't just decorative; it creates channels that improve airflow against the skin, which makes a real difference during active wear in warm climates. It's a design nod to the classic rubber straps that divers wore in the 1960s and 70s, updated with modern materials.

Navy is the colour choice here because it picks up the blue dial beautifully on the blue-dial HydroConquest, while also working surprisingly well with the black dial — adding a colour dimension that makes the watch feel more dynamic. The waffle texture gives the strap a retro-sporty character that suits the HydroConquest's dive-watch heritage perfectly. There's a playful quality to the combination that the plain rubber doesn't have.

This is the beach-holiday strap, the weekend-activity strap, the strap for anyone who wants their HydroConquest to look like it actually goes in the water.

Other waffle rubber options:

• Black CTS Rubber Waffle — the stealthy alternative; all the waffle texture in monochrome

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Casual — Black Sailcloth Signature

The HydroConquest is a dive watch — but it doesn't always need to look like one. The Black Sailcloth Signature Strap brings a nautical, technical aesthetic that bridges sport and casual territory beautifully.

Made from FKM fluoroelastomer rubber molded with a sailcloth weave texture, this strap gives you the look of traditional sailcloth without any of the drawbacks. No fraying, no water absorption, no break-in period. It's fully waterproof and sweat-resistant from day one, which makes it a genuine performance strap — not just one that looks the part. The woven texture adds visual depth that plain rubber can't match, giving the HydroConquest a more relaxed, weekend-ready character.

The Signature profile (4.5mm tapering to 2.2mm) adds substance to the 41mm case — there's enough visual weight to match the HydroConquest's proportions and give it real wrist presence. The calfskin padding inside ensures the strap moulds to your wrist over time while maintaining its shape. Black keeps things versatile and understated, working equally well with both the black and blue dial options.

Other sailcloth options:

• Navy Sailcloth Signature — picks up the blue dial and adds a nautical dimension that suits the dive-watch heritage

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The Wildcard — Red CTS Rubber (Plain)

This is where the HydroConquest shows a completely different side of its personality.

The Red CTS Rubber Strap is a bold choice — and that's exactly the point. On the black-dial HydroConquest, the red rubber creates a striking visual contrast that transforms the watch from a conservative dive tool into something with real visual impact. The colour combination is reminiscent of racing chronographs and vintage sport watches, adding a dynamic energy that the original bracelet simply can't provide.

The material is identical to the other CTS Rubber options — FKM fluoroelastomer, waterproof, UV-resistant, Cut-To-Size with deployant clasp. So you're not sacrificing any functionality for the colour statement. At 3.3mm, the strap sits flush and comfortable, and the bright red stays vivid over time thanks to the UV-resistant formulation. It's a strap that photographs exceptionally well and generates real wrist-check moments.

Why the wildcard? Because red is polarizing. Some people will love the bold contrast; others will find it too loud for a dive watch. If you're in the first camp — if you like the idea of a HydroConquest that turns heads rather than blending in — this is the strap that does it. And if you're on the blue dial, consider swapping the red for orange: the blue-orange complementary colour pairing is equally striking.

Other bold CTS Rubber colours:

• Orange CTS Rubber (Plain) — exceptional on the blue-dial HydroConquest; the blue-orange complementary pairing is a classic

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A Note on Buckle Colour

Match your buckle to your case — always. The HydroConquest is stainless steel, so you want a brushed silver or polished silver buckle. All Delugs leather and sailcloth straps offer a choice of buckle colour at checkout. For CTS rubber straps, the CTS Deployant Clasp in stainless steel is the natural match — it mirrors the bracelet's folding clasp feel and adds security during active wear.

How to Change the Strap on Your Longines HydroConquest

The HydroConquest comes on a bracelet from the factory, so you'll need to remove that first before fitting an aftermarket strap. The bracelet attaches via standard spring bars — a Bracelet Removal Tool makes this process significantly easier and safer, giving you the leverage to compress the spring bars without slipping and scratching the polished case surfaces.

Once the bracelet is off, all Delugs straps come with quick-release spring bars already pre-installed, making the process straightforward.

1. Prepare your workspace. Lay the watch face-down on a soft cloth or microfiber pad to protect the caseback and polished case surfaces from scratches.
2. Release the spring bar. Locate the small lever on the quick-release spring bar. Pull it back with your fingernail or fingertip to compress the bar.
3. Remove the strap. While holding the lever, angle the strap out from between the lugs. Repeat for the other side.
4. Insert the new strap. Slide one end of the spring bar into the lug hole. Pull the lever on the quick-release spring bar knob, guide the entire spring bar into the opposite lug hole, and then release the knob. You should hear a small click when the spring bar extends and seats into the lug hole.
5. Check the fit. Give the strap a gentle tug to make sure both spring bars are securely locked in. If there's any play, reseat the spring bar.

The entire process takes under a minute with quick-release spring bars — no spring bar tool required. The HydroConquest uses a 21mm lug width, and all Delugs straps in 21mm will fit perfectly.

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Frequently Asked Questions

What lug width is the Longines HydroConquest?

The Longines HydroConquest 41mm has a 21mm lug width. This is slightly unconventional compared to the more common 20mm or 22mm, but Delugs offers every strap in 21mm, so compatibility is never a concern. Make sure you're ordering the correct size — a 20mm strap will leave visible gaps, and a 22mm won't fit between the lugs.

Can you put a rubber strap on the Longines HydroConquest?

Absolutely — and it's arguably the most natural strap choice for a 300m dive watch. The Black CTS Rubber is the top overall pick because it matches the watch's sporty, water-ready personality perfectly. FKM rubber is waterproof, UV-resistant, and comfortable in any climate. For a sportier option with vintage texture, the Navy CTS Rubber Waffle adds a retro dive-watch feel.

How do I remove the bracelet from my HydroConquest?

The HydroConquest bracelet attaches via spring bars. You'll need to compress the spring bars from the gap between the solid endlinks and the inner lug surface. The safest way is with a Bracelet Removal Tool, which gives you the precision and leverage to compress the spring bar without slipping. Place a piece of tape over the inner lugs as an extra precaution against scratches. Once the bracelet is off, switching between aftermarket straps with quick-release spring bars takes under a minute.

What strap colours work best with the blue-dial HydroConquest?

Navy is the standout — it creates a tonal, monochromatic look that makes the blue dial feel like it extends down the wrist. Black is the safe, versatile option that works with everything. Grey bridges the two nicely. For bold contrast, orange creates a striking complementary pairing with the blue dial. Avoid warm brown tones — they can clash with the cool blue. When in doubt, stay within the blue-black-grey spectrum.

Is the HydroConquest too sporty for a leather strap?

Not at all. While rubber is the most natural pairing for a dive watch, the HydroConquest's clean dial design and refined proportions mean it translates beautifully to leather. The Black Epsom Slim is an excellent everyday leather option that tones down the sportiness just enough for the office. For formal occasions, the Black Alligator Signature transforms the HydroConquest into a legitimate dress-casual watch. Just remember: leather isn't water-resistant, so save it for dry land.

What's the best travel strap for the HydroConquest?

The Black CTS Rubber is the most practical travel companion — waterproof, durable, comfortable in any climate, with a deployant clasp that offers micro-adjustment for wrist swelling on long flights. For something with more character, the Black Sailcloth Signature gives you waterproof FKM rubber performance with a woven texture that looks more refined for dinners and sightseeing.

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Finding Your Strap

The Longines HydroConquest is one of the most versatile dive watches at any price — and it's an exceptional strap watch. The 300m water resistance and sporty design mean rubber is the natural starting point, but leather and sailcloth open up entirely new personalities. If you're starting out, the Black CTS Rubber (#1) is the safest first purchase — it matches the watch's dive-ready DNA, it's practically indestructible, and it works with both the black and blue dials. From there, add a Black Epsom Slim for everyday versatility and a Sailcloth Signature for casual weekends.

Use the Longines HydroConquest Strap Finder to see every compatible strap in one place, filtered to your exact reference.

Not sure which strap is right for your HydroConquest? Our team is available 24/7 via live chat — drop us a message and we'll help you find the perfect match for your watch, wrist size, and style.

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About Delugs

Founded in 2018 and headquartered in Singapore, Delugs is dedicated to elevating the experience of watch ownership through the simple yet powerful act of strap changing. We believe that straps are integral to how a timepiece is worn, perceived, and enjoyed. Our mission is to make strap changing a lifestyle — an everyday act of self-expression and versatility.

Delugs is an independent brand with a global community of clients, with a strong online presence and growing physical retail footprint. Our direct-to-consumer focus keeps us closely connected with the watch enthusiast community — fostering conversations, hosting events, and helping shape a more inclusive and expressive culture around watch collecting. We also work closely with watch brands to craft straps that complement their timepieces, bridging the gap between brand and collector, form and function.

Our catalogue spans leather, rubber, and fabric straps, with options for every watch and every occasion. We are committed to craftsmanship and quality, product design and innovation, and outstanding customer service. We offer watch owners the freedom to change straps as easily as changing outfits, and the opportunity to engage more deeply with the watches they love.

Visit our flagship boutique at Raffles Hotel, Singapore →

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— Marcus