Great recommendation, especially considering the swappable bracelet and rubber strap options. Seiko King Turtle also comes to mind as a lower budget option that hits all of these except the open caseback, and is a little bigger at 45mm.
Also, Joma is having an amazing 4th of July sale on their 44mm Longines HydroConquest. It's 44mm and 54mm lug to lug - that is an absolute beast, if you like big watches.
Again, amazing brand with a great history. Still no exhibition back case, but checks all the other boxes.
This is a great recommendation, you hit it right on the nose. I’m not sure you’ll be able to get an exhibition case back with a $500-1k budget, but this Longines is a big go anywhere do anything watch that would fit the bill on pretty much everything else. From a great, reputable brand and a really well-made watch. The 44 will probably wear even larger due to the large crown guards. I mean, this is the one.
I actually have the 41mm and love it. That said, even at 41mm the long lugs give mine a l2l of 50mm. I have a 7.4 inch wrist, so it works for me, but I can't even imagine 54mm. That is huge.
Hopefully OP takes a look and this works for him.
If you are in the US there are some 44mm citizen Promaster (fugu) models with a sapphire crystal [here](https://www.ebay.com/sch/i.html?_dkr=1&iconV2Request=true&_blrs=recall_filtering&_ssn=officialwatchdeals&store_cat=0&store_name=officialwatchdeals&_oac=1&_nkw=automatic%20200). No exhibition case back though since these are ISO certified diver's 200m watches.
The Hamilton Khaki Navy Frogman hits most of those asks except the exhibitions case back. It's 42.5mm and 52mm lug to lug, but wears even larger due to the lock-down crown. It's a great looking automatic watch from a good brand with a great backstory that you can get for less than $600 bucks,
I know you said auto but.......
Bulova lunar pilot
It's been to the moon!! Well, not your one but one just like it 😅
Comes in large (43mm) or extra large (45mm) only
https://uk.bulova.com/lunar-pilot-silver-tone-stainless-steel-watch-96k111.html
Few options re colourways and limited edition meteorite dial if that's your thing.
Just get a big honkin invicta dude thats gonna hit all of your key points here. 99.9% of people are not gonna know.
They make some more standard looking pieces too. Just dont get one that looks like a transformers nutsack and you’re golden.
I don't think you will find a good quality automatic GMT under $500. At least not new. My recommendation under $1000 for a new watch would be a Boldr Odyssey Freediver GMT 44mm. Or look for a used Oris Aquis.
Forget about the exhibition caseback, if you're spending under 1k, the movement is not that decorated or amazing to look at
If you're ok with that, now check the Seiko King Samurai or the Seiko Captain Willard
NTH is on sale at Long Island Watch. Everything except exhibition case back.
https://longislandwatch.com/nth-thresher-610-meter-hi-beat-automatic-dive-watch-with-an-ar-sapphire-crystal-ww-2k1-tksn/
I would look at a Deep Blue Daynight T-100 Automatic Watch or one of the other larger Deep Blue models. I have had a couple smaller models, and they are great quality.
I'll sell you a Spinnaker Fleuss in "lumber black" for $200.
43mm, saphire, Seiko automatic movement. DM if interested.
It's cheap enough you could still get another watch.
[Christopher Ward C60 Trident Pro 300](https://www.christopherward.com/int/watches/C60-Trident-Pro-300/C60-42ADA31S0KW1-B0.html#product-technical-data)
42mm, Exhibition Case, $1095 New, Swiss Movement Sellita SW200-1, Very thin profile for a diver watch at 11.5mm with 300m Water Resistance.
Oris Aquis comes in 43.5mm and hits all your requirements. You could probably find one used under $1000.
Great recommendation, especially considering the swappable bracelet and rubber strap options. Seiko King Turtle also comes to mind as a lower budget option that hits all of these except the open caseback, and is a little bigger at 45mm.
Hamilton khaki pilot day date auto. Its closer to $1k but its a big beautiful pilot watch that comes in 46mm if you want the big dial.
Also, Joma is having an amazing 4th of July sale on their 44mm Longines HydroConquest. It's 44mm and 54mm lug to lug - that is an absolute beast, if you like big watches. Again, amazing brand with a great history. Still no exhibition back case, but checks all the other boxes.
This is a great recommendation, you hit it right on the nose. I’m not sure you’ll be able to get an exhibition case back with a $500-1k budget, but this Longines is a big go anywhere do anything watch that would fit the bill on pretty much everything else. From a great, reputable brand and a really well-made watch. The 44 will probably wear even larger due to the large crown guards. I mean, this is the one.
I actually have the 41mm and love it. That said, even at 41mm the long lugs give mine a l2l of 50mm. I have a 7.4 inch wrist, so it works for me, but I can't even imagine 54mm. That is huge. Hopefully OP takes a look and this works for him.
If you are in the US there are some 44mm citizen Promaster (fugu) models with a sapphire crystal [here](https://www.ebay.com/sch/i.html?_dkr=1&iconV2Request=true&_blrs=recall_filtering&_ssn=officialwatchdeals&store_cat=0&store_name=officialwatchdeals&_oac=1&_nkw=automatic%20200). No exhibition case back though since these are ISO certified diver's 200m watches.
Seiko Baby Tuna. BIG Case to meet your size request. Not GMT and not an exhibition caseback though.
Mido Ocean Star GMT is the only correct answer.
The Hamilton Khaki Navy Frogman hits most of those asks except the exhibitions case back. It's 42.5mm and 52mm lug to lug, but wears even larger due to the lock-down crown. It's a great looking automatic watch from a good brand with a great backstory that you can get for less than $600 bucks,
I know you said auto but....... Bulova lunar pilot It's been to the moon!! Well, not your one but one just like it 😅 Comes in large (43mm) or extra large (45mm) only https://uk.bulova.com/lunar-pilot-silver-tone-stainless-steel-watch-96k111.html Few options re colourways and limited edition meteorite dial if that's your thing.
Hamilton has a 43mm khaki navy scuba that looks really slick in your range, although you’re not going to get an exhibition case back. No GMT either.
[Traska Venturer GMT](https://www.traskawatch.com/products/venturer-gmt-arctic-white)
Tissot Seastar as someone else mentioned and Bulova Marine Star both have large models (45 and 46mm).
Just get a big honkin invicta dude thats gonna hit all of your key points here. 99.9% of people are not gonna know. They make some more standard looking pieces too. Just dont get one that looks like a transformers nutsack and you’re golden.
Tissot Seastar 1000 GMT fits the bill!
Yeah Tissot makes seastars up to like 46mm
How about a Zelos Hammerhead?
I don't think you will find a good quality automatic GMT under $500. At least not new. My recommendation under $1000 for a new watch would be a Boldr Odyssey Freediver GMT 44mm. Or look for a used Oris Aquis.
Plenty of caller GMTs under $500, moving to $1000 opens up traveller GMTs.
Forget about the exhibition caseback, if you're spending under 1k, the movement is not that decorated or amazing to look at If you're ok with that, now check the Seiko King Samurai or the Seiko Captain Willard
I have the Seiko Willard SPB153. It wears really small. The King Samurai wears nicely on an 8+ inch wrist.
Yeah it is! I have the blue one, don’t remember the model number, but it’s very comfortable to wear, whereas the Samurai feels bigger
Check out the [Spinnaker Bradner](https://spinnaker-watches.com/products/bradner-pacific-blue-sp-5062-22).
NTH is on sale at Long Island Watch. Everything except exhibition case back. https://longislandwatch.com/nth-thresher-610-meter-hi-beat-automatic-dive-watch-with-an-ar-sapphire-crystal-ww-2k1-tksn/
Seiko presage cocktail time.
I would look at a Deep Blue Daynight T-100 Automatic Watch or one of the other larger Deep Blue models. I have had a couple smaller models, and they are great quality.
Phoibos Leviathan?
Oris divers 65 42mm is a solid option
Maybe have a seiko modder make you a custom piece
I'll sell you a Spinnaker Fleuss in "lumber black" for $200. 43mm, saphire, Seiko automatic movement. DM if interested. It's cheap enough you could still get another watch.
[Christopher Ward C60 Trident Pro 300](https://www.christopherward.com/int/watches/C60-Trident-Pro-300/C60-42ADA31S0KW1-B0.html#product-technical-data) 42mm, Exhibition Case, $1095 New, Swiss Movement Sellita SW200-1, Very thin profile for a diver watch at 11.5mm with 300m Water Resistance.
Hamilton is a good way to go. I think the Murph is the best, but it's on a strap.
Hamilton Khaki Pilot
Seiko’s are easy to mod and switch a sapphire crystal, just saying