As an engineer and a diver I liked the equations to prove the negligible effect of dynamic underwater activity in relation to static pressure. Love your site and your common sense approach.

Outstanding!!! Keep it going my friend. Nice one Marc, Best regards, TGV

HOLY SH** Marc, that was honestly the best watch technical video I have ever seen. I honestly got so hype when you brought out the equations. OMG. best ever.

This video really sold me on Seiko watches, I had no idea the difference in 200m resistance and Diver's 200 was so great, excellent and informative video!

Just started watching this series after I got a bit into watches. It's awesome. It really is a good sum-up for total newbies like I am. Thanks for all the effort and thought you have put into each one of these videos! We appreciate it.

We should apply ISO standards to politics and journalism. A standard of honesty must be met and maintained to become certified and untruths will result in revoked certification, rendering you unable to work until certification standards have been met once again. Marc, you're a genius!

i got extremely invested when you started showing the equations and i am not even an engineer or in college! dude knows his stuff! glad i know more about the water resistence with my gw9400 coming!

When I find the time I will binge watch an hour or so of your videos. This is the first I have commented on. Coming at this subject as a building engineer I give this video a 12 on a scale of 1 to 10. Just about every topic point covered and super easyu to understand. Great work, my friend.

Just started getting into watches and Long Island Watch was recommended to me by a few people. This is by far the most helpful series that I have yet to see. Look forward to seeing all the rest of content.

I've newly subscribed. Scuba dived many decades ago - it was fun, but nothing I felt I just "had" to do. Plus, it can be expensive. However, I never lost my love for dive watches. I. Own many at varying values, but always end up back at Seiko. They are such great watches at such a great value and can be Modded relatively easily. Love these videos. These are by far the best and clearest on the Internet. You are a great teacher and presenter. Thank you for scratching our dive watch itch!

This was even better than Part 1. And frankly, the math was the best part IMHO.

Thanks Marc! That was excellent. I use my dive watches for diving and they are both DIVER rated. I had no idea the testing was so stringent but now I feel even more confident that they've passed the tests. Also thank you for dispelling the myth of dynamic pressure. I was talking with a buddy this week that is an avid swimmer and he brought this up. I had no idea what he was talking about.

LongIslandWatches and UGC are two of my favorite channels on KZfaq. Great work Mr. Marc!

Great video and a clear explanation on water resistance Mark. As a scuba diver, it gives me some assurance that watch making industry has standards to meet in adding to safety. Thanks!

The definitive video to the water resistance question. Great job! I also appreciate the use of formulas at the end. Completely removes any confusion or doubt regarding that issue.

One of the best watch channels ever, you actually learn something useful. Thanks very much.

I’m really glad I found your channel from the Urban Gentry, I’m binge watching a lot of your videos even the old ones as you can see, I really appreciate your explanations and your attitude, you seem widely knowledgeable and I’m sure your friends and family appreciate you very much.

Thank you Mark for taking the time to make these videos. I have truly learned a lot from you and you inspire me to further my knowledge of horology. Cheers!

Thank you for this, far more information than I sought, none of it boring whatsoever, and it made my watch buying experience more fun. Kudos.

Amazing video series! Just got done with ep 5 and 6, I feel enlightened! Thank you so much! Hope you keep this series going. I just suscribed.

Love the content you put out. More power to you, brother!

Explained so well! After 10 years of watch interest, I still learned so much from this video, excellent job!!

Absolutely love this series, I cannot say it enough. Great knowledge to be had. Keep the videos coming Marc!

Thank you Mark. Very informative again. I am enjoying and learning from your great series!

The pressure equation was the cherry on top. Amazing video!

Great video! As a mechanical engineer myself, I appreciate the technical engineering discussion. Keep these videos coming!

I brought my Seiko skx007 from you guys . The service was great and the watch is beautiful , thank you for posting .

Thank you for making this so easy to understand. Will you start a math for dummies series?

Yeah, Mark, really good and insightful videos. I'm really waiting for each new episode and learn A LOT!

Brilliant video! My one nitpick: the little g in Bernoulli's equations is not the gravitational constant. It's the local acceleration due to gravity. The gravitational constant is big G and does not change. It really is a nitpick. Your explanations are wonderful. It's clear you have a background in engineering.

Awesome Marc, very kind of you to inform us making us that bit wiser! Cheers Mate!

Dear Mr. Mark, I am bingeing on your series and I should give you my regards for all of these information/facts you are sharing. From a fellow engineer, salute.

Watched lastnight Mark but unfortunately on an Xbox One can't comment even signed into my KZfaq account so commenting now. Great video. I'm watching your older videos slowly but surely! You have not aged from this old video to 6 years later in the present👊👊👊👊💪

Excellent. Thanks mate. I'm pretty new to this but I love watches. Your explanations are clear and understandable to a layman like me. Keep it up.

This is probably the most exciting watch video ever, great work!

Great video, watched the previous one to. I look forward to more of your watch & learn pieces 🙂

Great video again Mark. This is so educational and different from other channels. Keep them coming.

Nothing better to clear guesses and myths than bringing up the math.

I'm really enjoying these "Watch and Learn" videos, Marc. I'm not a watch guy. I now wear one because it's my fitness tracker, but I've never owned a mechanical watch (not sure I've even owned a quartz watch, now that I think of it). But I am fascinated by clockworks and intricate devices and machining. I happened to catch a documentary in the early days of HD that showed the creation of couple high-end, Swiss mechanical watches and I was fascinated by it. For some reason, I started to wonder exactly how jewels worked and what they were made of, which brought me to your #2 video in this series. Now I'm making my way through all of them. For the record, I've been interested to see what you looked like, so thanks for showing us your mug. Fantastic series!

Thank you Mark, I'm a diver and i liked this series on water resistance

Wow - love the engineering lesson in the end. You teach with great humility.

Mark, you are killing it! Absolutely love these videos! You're hitting on perspective for us watch geeks that I personally think is lacking. We ALL purchase a watch because we love the way it looks but for my engineering brain I want to know how it works. Thank you!

I always learn so much from your videos,please keep doing them.

"Everyday is a school day" is something I sprout to anyone that wants to listen. As a non-engineer , I learn heaps from your vids. Is it no wonder I purchase from you, thanks for the lesson.

Thanks Mark. I’m a bit late to the party, but this was by far the most informative video on water resistance I’ve found on KZfaq. Great content.

Im studying to be a mechanical engineer and Im avoiding my statics homework but sure enough you set me straight at the end haha thanks for helping to remind me my classes are truly relevant! Love the watch and learn series!

I never believed what was stated about movement force on a watch in water was a valid concern. Since I understand the math and physics of fluid dynamics I did not bother calculating it. I knew all along that the change in pressure exerted on the watch and seals due to motion would be nothing, relative to the weight of the water at X depth. Pressure is a function of resistance to flow, and a watch presents very little resistance. I concluded the concern about dynamic water pressure effects on watch seals was pointless. Glad you did the math though.

Clear, concise and to the point. Congratulations 👏

Great info, I just found your channel yesterday (recommended by TGV), These watch and learn series are my favorite, everything I wanted to know, nicely presented in an hour or so. Are you planning to do more of these, and if so, on what topic?

Marc, very insightful. Love your passion and unique product line.

I just ordered a Seiko SKX007K1! It's great to learn just what value for money I'm getting with such stringent criteria required to classify a certified diver's watch. I'd bought an Orient Ray 2 a fair few months back, but sadly the crown had popped out while I was swimming at the beach and it was too late when I realised salt water inside the dial. Note to myself - always check the crown before entering water. I'm looking forward to receiving my new (and first) Seiko and I love that Long Island Watch has an associated KZfaq channel. You provide a lot of useful information. (-: - Aussie consumer.

Another great informative video Marc! please keep uploading.

Excellent and infomative as ever, and a nice change to put a face on the voice we all know.... Looking forward to the next watch and learn, as l'm sure there's still a lot to cover in the future!!!

Wow how have I not seen this channel before. By far the best explanation on water resistance I have seen. And i loved the tiny bit of maths at the end. Greetings from a fellow engineer!

I was just doing wind calcs for a building today using the dynamic pressure equation. Excellent video!

Dude. This is awesome. It's an old video but I have to say your series of educational materials for watches are hard to find.

I am a Electronics Engineer; you are right on the mark regarding testing methods, and math calculations. Many watch makers will do a static test at 10 bars for few minutes and not facture temperature variables. I have a Citizen echo watch that was quite expensive, there is no screw on crown or back case, and it is rated at 20 bars. My very expensive Hamilton does have screw on crown and case back rated at 10 bars. I would trust the Hamilton over the Citizen for testing if I chose that path, "great discussion".

I was a scuba diver for about 12 years from mid 1980s to late 1990s. I would spend $15 to $25 for Casio digital watches labeled 50 meters and took them down, usually 50 to 60 feet, sometimes to 100 feet or a little more. Worked fine, never a failure. One of my instructors told me he had one in which the water pressure at 80 feet or so started pushing the watch’s buttons and it went crazy. Never happened to me. I swam with these watches, ran, rode bikes…they would take a licking. I would use them until the cheap plastic watchbands would break then it was back to KMart for another one. I no longer dive, but I swim with a Timex Ironman. I limit my Tissot and Omegas for more civilized environments. They say ignorance is bliss. I was a happy diver.

Fantastically informative! Thank you so much Mark.

This series is brilliant, thank you! Very informative, very easy to understand :)

Just loving these videos , great content. Keep up great work👍

Loved the video .. especially for those equations....brought back some other equations in my mind

Your videos are getting better and better!

It's like I'm going to online watch College! Great videos thanks.

Thank you for sharing your knowledge. Really great video.

thanks. that math's/physic's lesson helped me a lot understanding the trade [wristwatching: tissot seastar chronograph, 30 bars, blue-black dial - i love it].

Thank you! Very helpful topic. Great idea on fluid mechanic, the dynamic pressure is sometimes I never considered. I love your engineering perspective on to the watch.

Great video. Love this series. It takes the term, "watch nerd" to a whole new level.....and that's a good thing!!

That was very informative. You are a very good teacher, thank you for your knowledge. Bless

Math checks out. Great vid, thanks for doing that.

Remarkable. Absolutely remarkable. This is an amazing video. I've learned a lot! Thanks for posting it!

I learn, therefore I thank you.

Yo, I don't normally like or comment on videos but I've been loving this series. Keep it up man, there's not enough good watch educational videos on youtube. How to use a Divers Bezel would be cool like you mentioned. The same for using chronograph and moon phase/date functions. All those would be welcome additions to this. Though you can find them elsewhere on youtube, you're doing a fantastic job explaining things and it belongs all in one place.

Really good quality videos on this account!

Thanks for another fantastic video, Marc! Love these. Stony proud! :)

I have a quartz Rodania since 2002 with 50m WR. Used it many times while snorkelling at depths around 5-6 meters every summer. I have even cleaned it in 1:1 diluted spirit of salts (~9% nitric acid) to clear the gunk that accumulates over time. I have had is battery replaced in the store I purchased it and in other stores, too. Never had any signs of water getting into the watch. It has a screw in case back. I believe good brands usually under-promise these types of specs.

loving these, looking forward to the next one!

Another one out of the park, man! Thank you Marc.

Great info, thanks! Esp the dynamic pressure debunk. Also the info on ISO 6425, great stuff

I just love your lessons....Amazing!!

it's really a controversial subject. I reviewed my swatch Irony windfall, which I own for about 20 years. I use it for everything like swimming, showering, windsurfing etc.. never had an issue with it. I even use to operate the chronograph under water! As soon as one of my watches mentions water resistant, I'll take it for a swim although I try to avoid that if it's fitted with a leather strap..anyway, nice video! cheers

Fascinating and informative video. I look forward to more.

WO WO the man behind the hands love you content . you are the WIKI watch of youtube congrats.

Fascinating. Thank you. And well done for the Physics. Very welcome.

Love your videos!!!!! So interesting and informative 😘

Excellent episode, Mark, thanks!

I am so loving these videos!

Finally the face behind the hands. Wonderful especially the science part. I love the watch and learn episodes. A question. I noticed you are wearing two watches. What's your idea? I want to do that too.

brilliant video, really getting into your stuff!

Great explanations. Thank you. 👍

Great video…I learned a lot from this with which watch rating to buy for a true Divers Watch. Thank-you!

wow great Job! Super informative and useful! Thank you!

Thank you for the informative video Mark. I'd definitely have destroyed my watch otherwise. This motivates me to get a proper diver watch for vacationing and outdoors activities purposes.

Marc. Great video. i really love this series. Very interesting. The engineering perspective is great. BTW, what watches are you wearing? Thanks again.

Very informative.... Thank you Mark.

Well done Professor Marc 🙌 Definitely at least you know what you are saying and talking about, nothing compared with references this or that watch is etc etc ! By the way have two Certina’s iso certified iso 6425 that’s a plus have another Citizen Prodiver 200 meters divers certified, got one question for you do your Islander watches 200 meters ok for divers? Or you have to go to laboratory for iso certified your watches? Keep up with these very educational videos 💯 🔝

Excellent video. I’m no engineer but appreciate the engineering perspective of it.

Excellent. Many thanks.

love your videos Mark

Hi Marc. Pl do a review on Watch movements like ETA , Powermatic, tourbillon etc.