Underwater metal detector comparison

My Thoughts on the Garrett Mark II Vs. Fisher CZ-21

Underwater metal detectors are great for enthusiasts with a penchant for underwater treasure troves. The Garrett Mark II and the Fisher CZ-21 are two leading models in this specialized field.

Suppose you’re looking for entry recommendations for underwater detectors. In that case, the Garrett Mark II and the Fisher CZ-21 are right up there. But I know it can be difficult for potential buyers to pick between the two.

So, what sets these two metal detectors apart? I have a couple of pointers I’d like to share and probably help you narrow down your decision as efficiently as possible. Be sure to keep reading!

The Garrett Sea Hunter Mark II Vs. the Fisher CZ-21 Quick Silver

The Garrett Mark II and the Fisher CZ-21 are some of the industry’s highest recommended underwater metal detectors. If you’ve done your homework and checked out some forums, community posts, or- Reddit threads, you’ll come across other experts highly recommending these models.

Of course, there’s the cherry on top, the Minelab Excalibur II. Still, the Fisher CZ-21 and the Garrett Mark II are worthy contenders.

It is why I’ve dedicated this article to spreading the gospel on the Garrett Mark II and the Fisher CZ-21. But what sets the Mark II and the CZ-21 apart?

I’ve summarized several pointers you can use to put these models against each other. Hopefully, we can come out with an agreeable clear winner.

Let’s get started with a breakdown analysis of each of these models. If we can look at them separately, we can (maybe) objectively compare them, and maybe my thoughts on these two units can make sense as we move towards the grand finale.

Metal Detecting Tip: One of my most popular articles is all about getting wet metal detecting in rivers and streams. Read it -> HERE

Fisher CZ-21 Quick Silver Metal Detector Review

Fisher CZ-21 Metal Detector for Underwater
Fisher CZ-21 Metal Detector for Underwater – photo credit Kellyco

The Fisher CZ-21 is one of the two models Fisher created for their underwater line. The other underwater metal detector is the Fisher 1280X, but I’ve shared more on that below so that you can check it out.

For those that do not know, the CZ-21 was a replacement for the Fisher CZ-20. The company discontinued the CZ-20, and thus, the CZ-21 is currently the headliner for the Fisher underwater metal detector line.

Sales, Service and Parts are why folks TRUST Kellyco (biggest metal detecting dealer in USA) Highly recommended if you want the Fisher CZ-21 <-shortcut link

The Fisher CZ-21 has commendable features for anyone looking into underwater prospecting. Here are some of the main features of this model:

  • It is submersible up to 250 feet. This feature is pretty standard in underwater metal detectors, but it doesn’t hurt to mention.
  • You can use this model in either saltwater or freshwater.
  • Fortunately, you get manual ground balance with the CZ-21.
  • You get three operating modes: Pinpoint, Target I.D, and Autotune.
  • The CZ-21 offers a dual VFL search operating frequencies of 5kHz and 15kHz.
  • Fisher registered a controlled housing weight of 2.8 lbs. But it’s still on the lighter side.
  • Users get 8-inch and 10-inch coil options.
  • You also get a waterproof headset to boot.

Fisher revealed that the best environment for the CZ-21 is brackish water. I agree with that; the Fisher did perform well in brackish water. There’s little to complain about when the product functions like it’s supposed to.

Not only that, but they also recommend the CZ-21 for beach hunting, hunting in shallow waters, and lake hunting.

In my opinion, the Fisher CZ-21 is worth the purchase. If you want to go underwater hunting in brackish water, I highly recommend this metal detector. But what about the Garrett Mark II? Let’s look at what sets this metal detector apart from the rest.

Garrett Sea Hunter Mark II Metal Detector Review

Garrett Mark II Metal Detector for Underwater
Garrett Mark II Metal Detector for Underwater – photo credit Kellyco

Garrett is a household name in the metal detector industry. It goes without saying that many pros will recommend Garrett. They are a genuine and trusted brand, and I have yet to be underwhelmed by a Garrett metal detector.

Please note that Garrett is an older brand with many of its products needing, how do you say it, an upgrade. Take the Garrett AT MAX; it’s not an underwater metal detector. Still, it has a slightly tricky time competing with its more modern and innovative competitors.

If you’re ready to find out more about the Garrett Mark II here’s a shortcut link to the folks at Kellyco -> Garrett Mark II

Moving on from that, Garrett is still a good brand if you want to start underwater hunting. But is the Mark II worth the investment? Does the Mark II carry the same weight?

Here are some of the features Garrett offers on the Sea Hunter Mark II:

  •  The Mark II comes with verified Pulse Indication (PI) technology with 22 frequencies.
  • It comes with two search modes. The most popular mode is the Discrete Trash Elimination Mode.
  • Next up, the Garrett Mark II offers an operating frequency of 0.75kHz.
  • You get a submersion depth of 200 meters.
  • Users also get an adjustable length of 28″ to 52″ (.71m – 1.32m).
  • Garrett includes submersible headphones with the unit.

Garrett recommends the Mark II for saltwater and wreck diving use. Because PI technology can weigh down the unit, the Mark II comes with a hip mount belt or pouch to help distribute the weight.

Weight can be a massive problem if you’re not a skilled diver. However, if you do have your certifications and expertise in order, buoyancy shouldn’t be a problem when you’re underwater hunting. 

What do I think about Mark II? It’s a pretty good unit, but there could be more it could offer. The PI technology is an excellent addition; many high-end models utilize the PI tech other than the VLF. But it also means that the unit is not beginner-friendly.

Fisher CZ-21 Quick Silver Vs. Garrett Sea Hunter Mark II

It’s time for the juicy part. Here’s where we put the two models against one another and come up with a clear definitive winner. Is it the Fisher CZ or the Garrett Mark II?

 Garrett Mark IIFisher CZ-21
Price (as of writing)$637$1,169
Waterproof depth200 ft250 ft
Operating Frequency750 Pulses per second (PI)5kHz, 15 kHz  (VLF)
Weight5.2 lbs.5.7 lbs.
Interchangeable CoilYesNo
VibrationNoNo
Rechargeable Battery SystemNoNo
Submersible HeadphonesYes-IncludedYes-included
Score with 5 highest4.75

1.   Ground Balancing

If you hadn’t noticed, the Fisher CZ-21 comes with manual ground balancing. The user can now attune their unit according to the different underwater environments. On the other hand, you have the Garrett Mark II that doesn’t offer ground balancing.

It all goes back to Garrett products needing an entire overhaul to make their products more innovative. Many other underwater metal detectors offer ground balancing, and other prospectors might have ground balancing as a deal-breaker.

The Garrett has pre-set ground balancing, but I’m sure pros and intermediate experts will have negative things about that feature.

I think Mark II failed us in this regard. Ground balancing is a staple feature for metal detectors. Fortunately, the Fisher CZ-21 is doing a great job of providing the fundamentals to its consumers.

Is Ground Balancing Necessary Underwater?

I wanted to address this before diving into anything else. Ground balancing is an essential feature in any metal detector. According to Brandon Neice in his book,

The Metal Detecting Bible, Ground Balancing allows the detector to sense the earth as a baseline to find foreign or more significant metals.

Without Ground Balancing, the metal detector would fail to differentiate targets from the ground and the soil covering them. Does this apply underwater?

Yes, it does. Most of the targets you’ll be looking for while underwater won’t be drifting with the waves. As a solid object, it will have sunk to the ocean floor. Essentially, you’ll be hunting on the ocean floor, with sand being your primary inhibitor from the target.

Ground balancing will play a significant role in ensuring that your metal detector can find the targets with ease. Now that there’s some understanding of how ground balancing works underwater. We can move on to the rest of the comparison between the Mark II and the CZ-21.

2.   Submersible Depth

Again, the Fisher CZ-21 offers a deeper submersion depth than the Garrett Mark II. The Fisher CZ-21 offers a submersion depth of 250 feet, while the Garrett Mark II provides a submersion depth of 200 feet.

Now, the extra 50 feet might seem unnecessary, but it can make a massive difference if you plan on hunting in old wrecks. So, you have to give it to the Fisher CZ-21; the extra 50 feet is worth it.

Even the Minelab Excalibur II (the leading underwater metal detector) has a submersion depth of 200 feet.

Interestingly, PI is an excellent choice if you want depth; however, the Fisher CZ-21 offers a higher submersion depth than the Garrett Mark II.

The Fisher CZ-21 is offering more than that, which says a lot.

3.   Operating Frequency

Next up is the operating frequency. The Fisher CZ-21 provides two operating frequencies. A high operating frequency at 15kHz and a low operating frequency at 5kHz. In comparison, you have the Garrett Mark II with a single operating frequency of 0.75kHz.

Again, the Fisher CZ-21 is coming out on top. With a higher operating frequency, you’re more likely to locate high conductivity metals like gold.

Metal Detecting Tip: The frequency of your machine has a big influence on how effective it is. Learn more in this article What is the BEST frequency for Metal Detectors.

4.   Modes

The Fisher CZ-21 does offer three types of modes: Pinpoint, Target I.D, and Autotune. These modes are great for target identification while under the sea. Then we have the Garrett Mark II with modes of its own, but its most popular is the Discrete Trash Elimination Mode.

This mode will help your unit discriminate the trash and identify targets. It’s present to help combat the problems associated with the Standard mode in PI technology.

The Fisher CZ-21 doesn’t offer a unique mode like the Mark II. However, it will still help you discriminate the trash you encounter during prospecting. In this case, it’ll lie in the unit’s performance during discrimination.

However, I will have to give it to the Garrett Mark II. The unique mode to help discriminate trash is pretty endearing, and it works like a charm. So I have to give it to the Garrett Mark II. The unique trash discriminating mode is charming; what can I say?

5.   VLF vs. PI technology

If you hadn’t noticed already, the Fisher CZ-21 utilizes the VLF technology, while the Garrett Mark II utilizes the PI technology. Both metal detectors are suitable and used by metal detectors across the board.

So many factors go into whether VLF or PI is suitable for your hunt. Not only that, but there’s also BFO (Beat Frequency Oscillation) which is another metal detector technology.

PI is more expensive than VLF, and the fact that the Garrett Mark II offers PI technology at that price point is mind-blowing. Some manufacturers prefer to have PI on their underwater models, but it’s not mandatory.

Nevertheless, the difference between these two technologies is relatively minuscule. You will get optimum results whether you use VLF or PI. So, in this category, we can give it to neither. The manufacturers added these technologies to either solve a problem with the model or add to the model to enhance it and make it appealing to the market and general public.


I’m frequently asked what machine I use and recommend. No doubt about it, for the beginner get the Nokta Makro Simplex + Kit it’s the best. 100% waterproof, wireless headphones and pinpointer. Check prices and reviews with quick links below.

The next thing you need is a great shovel, believe me when I say you’ll dig more knowing you can dig FASTER. Links below to the nearly bullet proof Lesche T- Handle Shovel

Metal Detecting and Beaches are a perfect match. Sunshine easy digging and lots of people means dropped coins and jewelry. To search a beach affectively you’ve GOT TO HAVE A SAND SCOOP. CKG Sand Scoops are heavy duty and able to use as a shovel.

If it’s time up UP YOUR GAME and get the industry standard metal detector. The Minelab Equinox 800 IS THE BEST. Okay it’s not cheap, but your finds are going to increase with this machine. Shortcut links for reviews and current prices.


Metal Detectors for Beach and Seawater

The Garrett Mark II and the Fisher CZ-21 are not the only models created for underwater prospecting or hunting. There are several models across the industry marketed towards this specific niche. Here are some of the metal detectors suitable for beach and seawater:

  • The Minelab Excalibur II
  • The Fisher 1280X
  • The Nokta Anfibio Multi

Let’s discuss a few of these units. To keep you in the loop of what the industry is looking at in the underwater niche.

Metal Detecting Tip: Okay, beaches and Florida go “hand in hand”. Let me point you to some of the best beaches in Florida with this article. -> 7 Beaches in Florida to Metal Detect

The Fisher 1280X

Many users understate the value of the Fisher 1280X. It’s one of the two underwater models that Fisher offers. The other is the Fisher CZ-21 that we’ve come from discussing. What does the Fisher 1280xX offer?

The Fisher 1280X, like the CZ-21, offers a submersion depth of 250 feet. There must be some tradeoffs to balance the unit with a high submersion depth. The 1280X, unfortunately, has an operating frequency of 2.4 kHz. It’s lower if you compare it to the CZ-21.

Another issue with the 1280X is the weight. At 9.8 lbs., it is pretty heavy for an underwater metal detector. Lastly, the 1280X comes with a pre-set ground balance which is one of the reasons many users will overlook it.

Nonetheless, the 1280X is a great unit. It might not compare to the Garrett Mark II or the Fisher CZ-21, but it’s still a good enough unit to use on the beach. I would highly recommend this unit for beach use.

The Minelab Excalibur II

Lastly is the Minelab Excalibur II. This underwater metal detector has had praises sung about it. It’s a formidable opponent that can contest the Fisher CZ-21 and win with a clean sweep. What makes it so powerful?

One of its best features is the multi-frequency. Kicking off at 1.5 kHz up to 25.5 kHz. It has an undeniable reputation in the industry. I dare say it; it’s one of the best underwater metal detectors.

Another feature that sets it apart is automatic ground tracking. On an underwater metal detector, it’s pretty revolutionary. The Minelab Excalibur II is in its lane, and I would highly recommend it for expert prospectors.

In the End

Don’t be afraid to dive headfirst with either of these underwater metal detectors. Whether it’s the Mark II or the CZ-21, you have a good unit in your hands, and you will find success with that treasure trove. In my opinion, the Fisher CZ-21 is superior and will outperform the Garrett Mark II.


The East Coast Has Some Amazing Places to Metal Detect


David Humphries, Writer and Creator of METAL DETECTING TIPS. After borrowing my son’s detector and finding $.25. I felt like a treasure hunter. FREE MONEY! I was seriously bitten by the metal detecting bug.

Further Sources

  1. Brandon Neice, The Metal Detecting Bible: Helpful Tips, Expert Tricks and Insider Secrets for Finding Hidden Treasures (Berkeley: Ulysses Press, 2016), 128.  https://www.google.com/books/edition/The_Metal_Detecting_Bible/saXLsgEACAAJ?hl=en
  2. Cover picture photo credit Kellyco link

Scroll to Top