How Deep Can You Actually Go? Waterproof Metal Detector Ratings Explained

In metal detector, the term "waterproof" is used loosely, so it's worth asking what it actually means before you buy. Get it wrong one way, and you're out there in the surf with a machine tested only against splashes. Get it wrong the other way, and you've paid for 250 feet of scuba diving you'll never get to.

This guide will explain what the ratings mean, how water pressure affects a seal over time, if salt water makes a difference, why your headphones may not be rated for what your detector is, what gear helps you get a target back up from the water, and the handling practices that lead to warranty claim denials before water was ever the real issue.

Waterproof Doesn't Always Mean Submersible

Four terms get used almost interchangeably in product listings, and they are not the same thing.

What Does IP68 Actually Tell You?

IP68 is not a depth; it’s a certification of the IEC 60529 standard. The “6” indicates that the housing is dust-tight. The “8” means it can be submerged continuously deeper than 1 metre, but only to the particular depth and duration the manufacturer tested. One IP68 detector could mean 1.5 m for 30 min. Another could be 60 meters with no time limit. The rating itself tells you nothing about how deep you can go. The important number is the depth the manufacturer gives.

What Does "Water-Resistant" Mean vs. "Submersible"?

"Water-resistant" generally means the coil and lower shaft can be submerged in wet sand and shallow wading, while the control box remains dry. "Submersible" means the whole unit, including the control box, is designed to be submerged underwater.

What Does "Scuba-Rated" Really Mean?

Scuba-rated is the gold standard: sealed housing, tested for multiple dives at real depth, hardwired or purpose-built waterproof headphones, and no reliance on a battery door or headphone jack that can admit water under pressure. This is the category of the Fisher CZ-21.

Fisher

Fisher CZ-21 Quick Silver

250 ft submersible · dual-frequency VLF (5/15 kHz) · hardwired waterproof headphones

$1,579.00

Shop the CZ-21

How Deep Can an Underwater Metal Detector Actually Go?

Manufacturer-stated operating depths for the waterproof detectors we carry, deepest first:

Check the split. The CZ-21, Excalibur II, Sea Hunter, and PulseDive are made for real diving. The Equinox 900, Simplex Ultra, and ATX are designed for wading, surf, and shallow water work. Real waterproofing, just not scuba diving. Neither is “better.” They’re made for different jobs, and buying more than you’ll actually do in the water is just adding cost without adding usefulness.

The Garrett ATX is the odd one out on this list. It is the shallowest rated unit at 10 feet, but it is a pulse induction machine aimed at gold prospecting and heavily mineralized ground. It's waterproof, so you can work in creeks, wet sand, and surf without worry. But not so you can dive.

Garrett

Garrett ATX

10 ft / 3 m submersible · pulse induction · built for mineralized ground and wet sand

$2,379.95

Shop the ATX

Why Water Pressure Matters More Than the Rating Suggests

A detector doesn’t fail underwater because water “gets in,” vaguely. It fails at one particular weak point, and pressure is what finds it. Pressure increases with depth – roughly 1 atmosphere for every 10 meters (33 feet) of seawater. The housing is holding back about seven atmospheres at 200 feet. This pressure is exerted on all seal points of the unit, including O-rings, battery compartments, control housings, connectors, headphone ports, and cable entry points.

Can You Use a Metal Detector in Saltwater?

Yes, but saltwater changes the detection problem, not just the waterproofing problem. Salt conducts electricity. Wet mineralized sand throws off machines that aren't calibrated to deal with it. That’s why saltwater-rated detectors use automatic ground balance, pulse induction, or multi-frequency technology set to treat salt and black sand as background, not targets.

Here is where the Minelab Excalibur II is the gold standard. It can operate on 17 frequencies at once from 1.5 to 25.5 kHz, the BBS technology that allows it to read black sand and wet salt as noise, not false targets, the very problem single-frequency machines have in the surf. It is an analog detector with no screen, a conscious choice for underwater use, but there is nothing to glare-wash at depth, although it does mean a steeper learning curve if you are used to a target-ID display.

Minelab

Minelab Excalibur II

200 ft submersible · BBS multi-frequency (17 freq., 1.5 to 25.5 kHz) · the saltwater benchmark

$1,699.00

Shop the Excalibur II

Using saltwater also means the risk of corrosion, so rinsing your gear after each session is not optional maintenance. It’s part of what maintains the seals themselves for the long haul.

If you want pulse induction instead of multi-frequency in saltwater, the long-running Garrett Sea Hunter Mark II is the alternative. PI ignores salt and black sand by design. The Sea Hunter has a discrimination circuit that most PI machines don't have, so it skips more of the pull tabs and foil that usually go along with that technology.

Garrett

Garrett Sea Hunter Mark II

200 ft submersible · pulse induction · ignores saltwater and black sand

$769.95

Shop the Sea Hunter

Your Detector Is Waterproof. Are Your Headphones?

Wireless headphones introduce another constraint: Bluetooth and 2.4 GHz signals don't reliably travel through water, hence why serious underwater machines use wired, waterproof-rated connections. And here’s why the CZ-21 and Excalibur II come with a hardwired set of headphones that are rated as part of the sealed system, not a bolt-on accessory. If you have a separate wired waterproof unit in your setup, check the depth spec on the headphones themselves before you are 15 feet under, finding out the hard way.

The Affordable Way to Go Underwater

Not everyone needs 250 feet of scuba depth. If you’re wading, snorkeling, or working in shallow surf, the Nokta PulseDive gives you real underwater capability without the four-figure price tag. It doubles as a land pinpointer, so it’s not a single-use purchase.

Nokta

Nokta PulseDive Scuba Set

200 ft (IP68) · pulse induction · doubles as land pinpointer

$229.00

Shop the PulseDive

What You Actually Need for an Underwater Hunt

The detector is one piece. A few things around it decide whether the hunt actually works.

A Sand Scoop

This is the part people underestimate until they are standing in the surf digging by hand. The detector finds a target, but the sand is wet and sticks to it. It does not sift or fall away like dry sand does, so the real bottleneck is not the detection; it is the scooping and recovery of the target. It’s a dedicated sand scoop that turns a signal into a recovered target, rather than a long frustrating dig.

Screen Protector and Rain Cover

These prevent the display and housing from getting scratched or sand and grit working into a seam over repeated use. They are long-term protection for the unit and not something that will increase or maintain the waterproof rating of the detector. That rating comes from the seals themselves.

7 Mistakes That Can Compromise Waterproof Protection

1. Opening the battery compartment when wet. Any moment a seal is open is a moment the rating does not apply.
2. Skipping O-ring inspection. A cracked or flattened O-ring is the most common cause of a "waterproof" detector taking on water, and it is usually visible if you check before diving, not after.
3. Leaving sand or grit around seals. Salt crystals dry into battery doors and connector threads. Opening a compartment with dried salt on the seal is how grit gets past an intact gasket.
4. Using damaged cables or connectors. A nicked cable jacket is a failure point regardless of what the housing is rated for.
5. Assuming IP68 means scuba-rated. It does not. Check the manufacturer's stated depth.
6. Taking shallow-water equipment beyond its stated depth. A 16-foot-rated detector is not a 200-foot detector with a safety margin built in.
7. Skipping the rinse after saltwater use. Salt residue left to dry accelerates corrosion at exactly the seal points that keep the unit waterproof.

Fisher CZ-21 vs. Minelab Excalibur II vs. Nokta PulseDive

These three are the serious-diving tier, and each answers a different need.

Fisher CZ-21: the deep-diving option. Depth rated to 250 feet. Dual frequency VLF at 5 kHz and 15 kHz with automatic saltwater compensation. Permanently attached waterproof headphones. 3-tone audio ID. 2-year warranty. Not for just wading, but for a person who dives or works heavy surf on a regular basis.

Minelab Excalibur II: the saltwater specialist. BBS multi-frequency technology designed to read saltwater and black sand as background instead of false targets, hardwired Koss headphones and NiMH pack good for 14 to 19 hours, submersible to 200 feet. Main use case is pick if saltwater beach and underwater detecting.

Nokta PulseDive: A cheaper alternative for underwater use. IP68 rated to 200 feet. Pulse induction stable in salt and mineralized ground. Up to 25 hours per USB charge. Converts to land pinpointer. This is the answer for someone who wants real underwater capability without stepping into the $1,500-plus category.

Which Waterproof Metal Detector Should You Buy?

Choose the Fisher CZ-21 if you plan to dive deep and want a purpose-built underwater detector. Shop it here →

Choose the Minelab Excalibur II if saltwater beach and underwater detecting are your primary use case. Shop it here →

Choose the Nokta PulseDive if you want an affordable, compact underwater option. Shop it here →

Choose the Minelab Equinox 900 if you mostly hunt beaches and shallow water rather than scuba diving.

Minelab

Minelab Equinox 900

16 ft / 5 m (IP68) · Multi-IQ multi-frequency · surf and shallow water

$999.00

Shop the Equinox 900

Choose the Nokta Simplex Ultra if you want a more accessible beach detector with genuine shallow-water capability. Shop it here →

Nokta

Nokta Simplex Ultra

16 ft / 5 m (IP68) · 15 kHz VLF · vibration alert for low-visibility water

$299.00

Shop the Simplex Ultra

Frequently Asked Questions

Bottom Line

Get the machine that you are actually going to use it for. The CZ-21’s 250-foot rating and dual-frequency saltwater handling justify its cost for those who regularly dive or work heavy surf. Serious underwater work requires the saltwater standard, and it’s the Excalibur II that is the go-to machine for seasoned detectorists. Want real underwater capability without the investment? The PulseDive goes to 200 feet for a fraction of the cost. Mostly wading and surf hunting rather than diving: the Equinox 900 or Simplex Ultra covers that use case without paying for depth you will not use.

Whatever you choose, the rating on the box is only part of the story. Whether that rating holds up depends on the headphones, the O-rings, and how you handle the unit between uses.