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What is the Best Underwater Metal Detector? Tips on Where to Find Submersible Equipment

Complete guide on the best under water metal detectors

Best Underwater Metal Detector

Not all treasure is found underground. In fact, some of the best treasures around are located in the water. That’s why, for many treasure hunters, buying an underwater metal detector is a must. 

A good product can take you from land to sea without delay. If you want to take this hobby to the ocean, you’ll need to find a submersible metal detector. If you intend only to use your equipment to search near stream beds and on beaches, then a water proof model will suit your needs just fine.

An underwater detector is one that can be partially or completely submerged in H20. It’s important to look at these types of models specifically if you want the option of exploring shipwrecks, because you can’t use ordinary models beneath the ocean without ruining them.

A waterproof gold metal detector is a must for searching streams where gold deposits have been found. Since gold flakes and nuggets are often found beneath the sea, any serious gold hunter needs a submersible model to find the treasure they seek.

Guy diving underwater

It’s important to note here the difference between a waterproof and a water resistant metal detector. Typically, the former can be used in the rain and in and around H20. However, prolonged use in liquid can damage them.

We want to note here, too, that not every underwater detector can be used in salt water. If you intend to do any ocean treasure hunting, look for products that are built to withstand this mineral.

Because we know that deep sea treasure hunting is a popular hobby for serious seekers, we’ve put together this guide to help you determine the best liquid proof metal detector for your treasure hunting needs.

Top 3 Best Waterproof Metal Detectors


Garrett Infinium

Garrett Infinium


Fisher CZ21-8


Tesoro Tiger Shark

To begin with, we have chosen three of the best underwater metal detectors on the market to review. To choose these, we sorted through the features and specifications of many of the best submersible models to find those that we felt confident were the best available.

1. Garrett Infinium

Garrett Infinium Screen

Our first pick for the best underwater metal detector is the Garrett Infinium. This piece of machinery is for those more serious treasure that aren't afraid to get wet. We had a great time playing around with this particular model because of the variation of features it includes. There was lots to learn from this product and here are just some of the things we did. 

Features and Specifications

We always like to start our reviews by looking at the main features of the products we are reviewing. This metal detector has many features that we like. First thing, the waterproof concentric coil on this model is sturdy.

The next key feature and this is an important one, is that the Garrett Infinium is designed for underwater metal detecting use in both fresh and salt water. Some models detectors are only suited for fresh water, so this is a key, consideration for those treasure hunters who want to get serious about finding a waterproof gold detector for sale to use at the beach.

garrett infinium coil

We also really like that this product has both All Metal Deepseeking Mode Audio Threshold and Adjustable Audio Tone ID Discrimination. These features are important in a subersible metal detector that can be used both for hunting clad coins and precious metals because they help treasure hunters distinguish their finds easily. This model also comes with a headphone jack for underwater use.

Full range pulse induction is another great feature of this product. With this feature, you can be confident of locating even metal that’s been buried deeply in the sand.

This is a great waterproof metal detector for finding coins, treasures and precious metals on land, in fresh and in salt water. 

Size: 4.6 x 12.7 x 26 inches

Weight: 9.4 pounds


Now let’s review some of the most significant benefits that you can expect to reap if you choose the Garrett Infinium as your waterproof metal detector of choice. 

  • This is a model that can take you from your backyard to 200 feet under the sea without difficulty, it’s a very versatile machine.
  • The sensitive coil and pulse induction technology make this a very accurate machine and satisfying to use since it can find many different kinds of treasure.
  • It functions well as an underwater gold detector where other submersible metal detectors do not.
  • This is a very sturdy submersible metal detector that you can expect to last you for years.

Pros and Cons

While there are many things we love about the Garrett Infinium, there are a few things that could be better as well. Here are the main pros and cons of this underwater metal detector:

  • The versatility of this machine is great since it can be used on land, in fresh and in salt water.
  • This product is safe to use down to 200’ beneath the ocean, making it ideal for metal detecting on and around shipwrecks.
  • It’s a highly sensitive model and we think it is the best for finding gold beneath the sea.
  • We have found this model to be very sensitive to “skywave” interference, so it’s not ideal for use in areas with a lot of electricity in use or near cell phone towers.

Our Final Verdict

My cousin Billy was in the market for a waterproof metal detector and we asked him to help our group with testing the equipment. Most people had great luck with it diving although, Billy pointed out that its heaviness made it impractical to use on land, which means it's use is specifically in water, but man was a great tool for underwater action. The Garrett Infinium’s accuracy underwater made it our top pick in this category if you dream of being an underwater treasure hunter.

We think you’ll love the Garrett Infinium, particularly if you dream of searching shipwrecks and becoming a master underwater treasure hunter.

Judge Final Verdict

2. Fisher CZ21-8

Fisher CZ21-8 Product

Our second pick is the Fisher CZ21-8. This is an extremely versatile waterproof metal detector and we loved all the extras it had to offer. When testing this beauty out, there were so many specifications to learn it was really fun handling such an advanced machine. Here's everything we learned about the Fisher CZ21-8. 

Features and Specifications

The first feature is the versatility of this underwater metal detector. It can be used in both shallow and deep water, in fact, this model can be used to depths of 250 feet, making it one of the most versatile products on the market. It’s also safe for use in both fresh and salt water so that it can be used in lakes and the ocean as well as in streams and rivers.

We also really like the dual frequency fourier domain signal analysis, which gives this model superb sensitivity and the ability to distinguish between different types of metal easily. The all-metal auto-tune mode is reliable and makes this machine ideal for use in highly mineralized soil. In other words, this detector also happens to be one of the best water proof models for gold hunting.

Fisher CZ-21 warranty

Speaking of audio features, we appreciate the Fisher’s 3-tone audio target ID. It has a large target alert and a faint target audio boost that you can use to hone in on distant treasures or those that are deeply buried and both features are a must. 

Another feature we like is this machine’s precise pinpointing, a feature that’s a must if you’re in the market for an underwater metal detector.

Digging in sand is hard work and having a top-notch pinpointer can save you a lot of time, effort and energy while you’re unearthing the treasures you find.

Size: 6 x 12 x 21 inches

Weight: 6.6 pounds

At 6.6 pounds, this product is significantly lighter than some of the other professional grade metal detectors, waterproof or otherwise, which is a major bonus. 


Now, let’s take a look at some of the biggest benefits of the Fisher C721-8. There are some significant advantages to choosing this model over the others on the market, which is why we have included it in our best waterproof metal detector reviews.

  • This is a very versatile machine that’s good for use on land and underwater, you won’t have to worry about having a machine for both terrain.
  • You have the option of choosing an 8” or 10” coil for use with this product so you can swap it out to get into tight places if you need to.
  • This model is very sturdily built and is likely to last you for a very long time if you invest in it.
  • Most submersible metal detectors are quite heavy, but this one is relatively light by comparison, which is one of the reasons it gets high scores from us
Fisher CZ21-8 Model

Submersible metal detectors ratings are often reliant on versatility and sensitivity and the Fisher scores high on both counts.

Here's a pretty entertaining demonstration video.

Pros and Cons

Now let’s review some of the pros and cons of the Fisher C721-8. We think this is an excellent choice, but obviously it’s not perfect. Let’s start with the pros and cons of the Fisher C721-8:

  • This machine is highly accurate and you can count on it to help you distinguish trash metal from gold, jewelry and valuable coins.
  • Unlike some of the other detectors on the market, this machine is truly resistant to liquid, especially since Fisher updated the pinpointer, it’s very unlikely you’ll have to worry about a leak with this product.
  • This machine does a very good job of finding gold and it works well on salt beaches and in heavily mineralized soil.
  • The price tag is quite high and it may be too high for some amateur treasure hunters and hobbyists.

Our Final Verdict

The Fisher CZ21-8 Underwater Metal Detector is a machine we like for its accuracy and versatility. Again Billy’s take was that it’s the sturdiest of the models we’ve chosen and the vote was pretty much unanimous. He had good luck searching with this underwater and found it easier to use on land than the Garrett Infinium. He also mentioned that the pinpoint function was particularly good with this model. 

Our final verdict is that the Fisher CZ21-8 Underwater Metal Detector is a very good product for use by serious treasure hunters who want a high degree of accuracy and versatility, but want to be able to use it on land also. 

Man with hammer

3. Tesoro Tiger Shark

Tersoro Tiger Shark

Our final pick in this category is the Tesoro Tiger Shark because it was surprisingly affordable which may help ease some of the sticker shock if you’re considering upgrading to an underwater metal detector. It's packed with value for the price which is why it's made the cut in our top 3. Here's what we found when testing out this product. 

Features and Specifications

The Tesoro Tiger Shark has some very nice features that make it worth of consideration as the best underwater metal detector on the market. Here are some of the things we like most about it.

First, the Tesoro Tiger Shark has a drop-in battery design. That might not seem important, but it is if you have to change your battery in a hurry. With other designs, the battery leads may be subject to breakage if you rush or get careless. The drop-in design is more stable and decreases the chances that something will break.

Second, we really like the fact that the Tesoro Tiger Shark makes it extremely easy to switch between fresh and salt water modes since these two locations require different detecting criteria. You won’t have to remember any special controls or techniques because this model takes care of them for you with the flip of a switch.

Tersoro Tiger Shark Screen

The full discrimination adjustment mode is another nice feature on the Tesoro Tiger Shark. This feature makes it easy for you to filter out the background noise created by junk metal and trash and hone in on the treasures that are worth your time and attention, like gold jewelry, coins and other valuables.

This product is fully waterproof up to 200 feet of H20. Its sturdy construction and exterior controls make this is a wonderfully reliable metal detector for treasure divers.

Tersoro Tiger Shark Product

Size: 4.9 x 14 x 22.4 inches

Weight: 7.1 pounds

As was the case with the other models we tested, that makes the Tesoro Tiger Shark a little heavy for land use but perfect for underwater. Using a strap can help reduce fatigue when you’re on land.


What are the benefits you can expect to enjoy if you choose the Tesoro Land Shark?

Here are some of the biggest benefits we’ve identified while using it:

  • This machine is particularly good at finding gold chains underwater and very few of the other detectors on the market can do that.
  • The degree of precision that’s attainable with the help of the noise filtering feature is very good and ensures that you won’t waste time digging up junk.
  • This machine is very good at finding deeply buried coins and treasures up to 16” underground.
  • The relatively low price means that you can earn back your investment quickly.

Pros and Cons

We like a lot of things about the Tesoro Tiger Shark, but there are also a few things we think could be better. Let’s look at the pros and cons of this machine:

  • The affordable price tag puts the Tesoro in range for people who want to try ocean treasure hunting but don’t have more than a thousand dollars to spend.
  • The Tesoro has a leg up on other models because it has the ability to pick up on treasures between 12” and 18” below the surface of the ground (or sand).
  • Of all the waterproof products on the market, this one is probably the best on land.
  • The controls could be more accessible, some are on the outside, but others are behind the battery pack and they can be somewhat difficult to get to.

Our Final Verdict

Everybody who helped us test the Tersoro Tiger Shark loved this underwater metal detector. Some reported, it was better than the other models at locating treasure on the ocean bottom, although when I used it myself, I did think to myself that I wanted to get a chest strap if I was going to use it for a long dive. This model’s affordable price and accuracy make it an easy choice as one of our Top 3 underwater metal detectors.

The Tesoro Tiger Shark is much more affordable compared to others on the market while still offering some great features and benefits. 

Judge figure holding mallet

Things to Consider When Buying a Model That Gets Wet

Man searching online

When we talk to new people about underwater metal detectors, it’s common for us to hear concern about the prices. These are not inexpensive machines and so we sometimes hear questions like:

  1. Can I build a DIY underwater metal detector?
  2. What about a used underwater metal detector?

Let me make myself clear, we advise AGAINST trying to build your own waterproof model. Here’s why...

If you take a regular metal detector and try to rig up some kind of liquid resistant casing for it, the most likely result is that you’ll have a product. Many standard models have waterproof coils, but that doesn’t mean that they’re truly waterproof.

If you take a standard metal detector into the ocean with you and especially if you try diving with it to depths of more than a few feet, it’s unlikely that your waterproof casing will hold up. Liquid will leak in and ruin your metal detector and you’ll be left wondering why you tried to mess around with it.

Boy Crying

Used submersible hunting equipment is a different story, or at least, they can be. If someone is selling a high-quality submersible metal detector, there’s no reason to believe that it can’t be an option provided that you trust the seller and have a chance to test it out.

The main concern with buying a used product is that you might end up with a damaged machine. The best way to guard against that is to buy from a reputable dealer and ask to take the machine for a test drive before you buy it.

Now, let’s review some of the most important things to look for when making the decision to buy this piece of machinery.

1. Detection Type

Most metal detectors waterproof fall into two categories: VLF (very low frequency) or PI (pulse induction). Pulse induction models tend to be more expensive, but there are some benefits to choosing a VLF model, too.

The main distinction between the two types is that pulse induction models are not sensitive to ground mineralization and may be better for use on salt water. However, they also don’t do as good a job of filtering out junk, so you may spend more time in unnecessary digging than you would with a VLF detector.

By contrast, VLF detectors don’t get as distracted by so-called background noise from junk. They may be better suited to finding jewelry and relics and they’re better in fresh water than PI detectors.

2. Depth

If you intend to use your product for diving, then the depth that a particular metal detector can handle is a very important consideration in the buying process.

As you saw in our reviews above, some models can work in very deep water, up to 250 feet below the surface. Anybody who intends to dive and seek treasure at shipwrecks or in deep lakes should be thinking about the ability of the product to withstand the pressure of diving.

Why does depth matter? If you take a submersible metal detector too deep, it may cease to work. The extreme pressure of the liquid above it can leak into the product and damage it. In the case of salt water, the exterior may not be able to withstand corrosion from salt while the interior of the machine may be too sensitive to it.

Any serious diver in the market for an underwater model should opt for the sturdiest machine that can handle serious depth, that way, you won’t be caught unawares or risk damaging your equipment on a dive.

3. Accuracy

Under the Sea

Another key consideration when buying a waterproof model is its accuracy. If you intend to dive with your metal detector, keep in mind that objects in the sea can sometimes be buried very deeply in sand or dirt. The movement of liquid can turn an object on the sea bottom into buried treasure very quickly.

The depth perception and accuracy of these types of detectors can vary greatly from model to model. If you have experience diving in certain areas, you may have an idea of how deep you’ll have to dig to unearth treasures. Keep that in mind when comparing different models.

4. What Else Will You Use Your Metal Detector For?


Do you have the budget to have more than one quality metal detector? If you do, then you can probably skip this section and go on to the next. However, if you want a multi-purpose model, keep reading.

Some underwater products are very good on land, too. The very best models can be used in both fresh and salt water as well as on land.

However, it’s important to keep in mind that many underwater models are quite heavy, much heavier than regular products. If you intend to buy these types of metal detectors for use both in water and on land, then you’ll want to make sure to choose the lightest model you can find that still suits your needs. You may also want to consider a chest strap to take some of the weight off your arms while you’re out hunting.

5. Accessories

Some waterproof models come with accessories and others don’t. If you intend to dive while using your metal detector, then it’s very important to get waterproof headphones to use with it. That means you’ll want a product with a headphone jack and you may want to look for a model that comes with headphones.

You may also want to consider looking for models that come with carrying bags, straps, additional coils, instructional books and DVDs and other extras. Since most submersible detectors are quite expensive, these little extras can make a difference in how you feel about paying the price being charged.

6. Budget

Budget money in Jar

The final consideration, of course, is your budget. Since many waterproof models are quite expensive, you’ll have to figure out what you can afford to spend. Keep in mind that you may end up paying more for a cheap product in the long run if it breaks and you have to replace it. 

People who know they’re into treasure hunting for the long haul may want to save up for a high-quality model rather than risking a disaster with a cheaper version.

So, What's the Best Underwater Metal Detector For You?

Man looking out to sea

Ultimately, you are the only person who can decide what the best underwater metal detector is for you and your needs. There are a lot of different versions available and we hope that our reviews here and the other information on this page, will help you to make an informed decision. You deserve a product that will last you for years and help you find the treasure you desire.

However, if you want to go back and keep reading about the various different types of models in the market because you don't want to make a decision until it's an informed one, click here for more information on the best metal detector reviews.

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