The 38mm Aqua Terra is the quiet one. Same teak dial, same Master Chronometer movement, same 150m of water resistance as its bigger brother, but it sits flat under a cuff and never announces itself. For a lot of people it ends up being the only watch they actually need.
It is also the single most misquoted Omega on the internet when it comes to strap size. So let's fix that first, because getting this wrong is the difference between a strap that clicks in and a strap that goes back in the post.
The fit: your 38mm Aqua Terra takes a 19mm strap
Write it down: 19mm.
Not 20mm — that is the 41mm Aqua Terra, and it is the number most people assume applies to the whole family. Not 18mm either, which gets quoted surprisingly often online and is simply wrong for this case. The 38mm reference 220.10.38.20.03.001 is 19mm at the lugs, and so is every other 38mm reference in the 220.10.38.20 range regardless of dial colour.
If you are ordering from our Aqua Terra collection, there are two dropdowns on the product page and both matter:
Lug Width — select 19mm. The dropdown opens on 18mm by default, so this is the one to change before you add to cart. Do not leave it on the default.
Buckle Colour — this depends on what you already own. The strap is cut 105mm + 105mm, the symmetrical layout made for a folding clasp, and it is built to work with your original Omega buckle. If you have that clasp already, choose No Buckle and reuse it. If your watch came on the bracelet and you have nothing to fasten a strap with, choose Silver to match the steel case — gold and rose gold are also there, but on a steel 38 they will look bolted on.
Spring bars come with every strap. If you would rather not fight the lugs with a screwdriver, the Omega strap installation tool makes it a two-minute job.
That is the whole sizing story. One number, one dropdown, done.
Some background on this reference
The Aqua Terra has been in the Seamaster family since 2002, but the version most people picture arrived with the third generation, which set the line at a 38mm and a 41mm sitting side by side. The 38 is not a women's model or a compromise size — it is the same watch with three millimetres taken out of the case, and on a wrist under about 7 inches it is the better proportioned of the two.
Reference 220.10.38.20.03.001 is the blue one: a sun-brushed blue dial with the horizontal "teak" pattern that Omega borrowed from the wooden decks of sailing yachts, rhodium-plated hands and indexes filled with white Super-LumiNova, and the date sitting at 6 o'clock instead of the usual 3, which keeps the dial symmetrical. Inside is the Co-Axial Master Chronometer calibre 8800, METAS-certified and resistant to magnetic fields above 15,000 gauss. Water resistance is 150 metres.
That last number is the one people forget. This is not a dress watch with a dive-watch spec sheet — it genuinely swims. The reason most owners never use it is that they are wearing a polished-and-brushed steel bracelet they would rather not scratch. A rubber strap removes that hesitation entirely, and it keeps the bracelet in the condition it was in when you bought it.
What the dial gives you to work with
Blue sun-brushed, with a horizontal grain that shifts as the light moves across it, plus bright rhodium hands and white lume against it. Steel case, steel bezel-free profile, no third colour anywhere.
Two things follow from that. First, the dial changes tone constantly — deep navy in shade, bright mid-blue in sun — so a strap does not have to match one exact shade of blue to work. Second, the teak pattern is a sailing reference, which means blue and white on this watch is not a costume. It is the theme the designers already used.
Four that work.
1. Blue and white — the one the watch is asking for
Blue body, clean white line. Against the teak dial it reads as deliberate rather than matchy: the blue picks up the dial, the white line picks up the lume and the printed minute track, and the whole thing lands squarely in the sailing language the dial is already speaking.
It is also the best-selling strap in the Aqua Terra collection, which is usually a good sign that people are seeing what you are about to see when it arrives. Blue/White rubber strap →
2. Full blue — the tonal option
No contrast line, no interruption. The watch becomes one continuous run of blue from clasp to clasp, with the steel case as the only break in it. This is the more grown-up version of the same idea and the one to pick if the blue-and-white feels a touch nautical for the office.
It also does something specific to a sunburst dial: with a solid blue strap below it, the dial's shifting tone becomes obvious, because you have a fixed blue right next to it for comparison. Full Blue rubber strap →
3. Full black — make the dial the only colour
The neutral. Black rubber removes every competing tone from the wrist, so the blue dial is the only colour left on the watch and it looks considerably richer for it. Sharper under a suit than either blue, and the one that makes a 38mm case read as a serious watch rather than a small one.
If you own one strap besides the bracelet, plenty of people make it this one. Full Black rubber strap →
4. Light blue — for the two months a year you need it
Not an everyday strap, and it is not trying to be. Light blue against a deep blue teak dial does what a lighter tone always does: it lifts the watch, pushes it into holiday territory, and looks completely at home next to water.
Given this watch is rated to 150 metres and you are finally willing to test that, it earns its place. Light Blue rubber strap →
If you want the contrast-line look without the blue, Black/White is the same idea in a more neutral register.
Owners of the other sizes
Same collection, different number in the dropdown:
- 41mm Aqua Terra — 20mm, not 19mm. Full breakdown in our Aqua Terra 41mm strap guide.
- 43mm Worldtimer — 21mm. See the Aqua Terra Worldtimer 43mm guide.
- Every other Omega — the full set of model guides lives in our Omega strap guide index.
Measure once, order once. Almost every wrong-size return we see on the Aqua Terra comes from someone assuming all of them are 20mm.
Ready to change it?
Helvetus is one of the largest names in aftermarket luxury watch straps, and every Omega strap we make is cut to a specific case rather than trimmed from a universal blank — which is why there is a 19mm option in the first place.
All rubber straps carry a lifetime warranty. Shipping is free worldwide, there are no import costs wherever you order from, and more than 50,000 customers have already made the swap.
Browse all Aqua Terra straps → See the full Omega strap range →
Helvetus is not affiliated with Omega SA. Model names are used for compatibility reference only.
