This article will review the Garrett Sea Hunter Mark II pulse induction metal detector. We will talk about important features of a good underwater metal detector and compare the Sea Hunter Mark II to 3 other top underwater detectors: Minelab’s Excalibur II, Tesoro’s Sand Shark, and Garrett’s Infinium LS.

And to better help you, please use our interactive guide below to see how the Garrett Sea Hunter compares to other noteworthy detectors on the market:

PhotoModelPriceFeatures
Bounty Hunter Gold DiggerBounty Hunter Gold Digger$7" Weather Resistant Coil
Garrett Ace 400Garrett Ace 400$$$8.5 x 11" DD coil
XP Deus Wireless2XP Deus Wireless$$$11” DD Coil
Garrett AT Max$$$Waterproof to 10 feet
Bounty Hunter LSTAR Land StarBounty Hunter LSTAR Land Star$$8" Search Coil
Fisher F22Fisher F22$$9″ Triangulated Concentric Coil
Bounty Hunter TK4 Tracker IVBounty Hunter TK4 Tracker IV$8” Waterproof Coil
Minelab Equinox 600$$$Ideal for beach, rivers, streams and lakes
Minelab Vanquish 540$Search Modes: Coin, Relic, Jewelry, Custom, All Metal
White’s TreasuremasterProWhite's TREASUREPro$$$10" DD Waterproof Coil

Meet the Garrett Sea Hunter Mark II

The Garrett Sea Hunter Mark II ($750) is designed for underwater metal detecting. The Sea Hunter is a pulse induction (PI) metal detector that works very well in fresh or saltwater areas. Because this is a PI machine, it is great at compensating for highly mineralized soils and saltwater. Most very low frequency (VLF) metal detectors have trouble with highly mineralized ground conditions and saltwater. But the Garrett Sea Hunter Mark II overcomes these issues with PI technology.

The Sea Hunter is fully submersible up to 200 feet. It has neutral buoyancy, so it is easy to keep on the sea or lake bottom without struggling. It has configurations so it can be used underwater, on dry land, in the mud, or in the surf. The 4 mounting and stem arrangements can be configured to your needs. Mounting options are long stem with top stem mount, under cuff stem mount, hip mount, and short stem ScubaMate. 

The Sea Hunter Mark II User Manual has great descriptions and pictures of each configuration to make it easier to choose the right one for you. The ScubaMate configuration is ideal for divers while the long stem configuration allows users to carry the control housing on the waist or shoulder. Stem mounted is most useful for searching on land or in shallow waters.

This model was developed with expert divers in mind and it is important to remember that if you want to use this detector to its full depth of 200 feet, you should be an experienced diver and SCUBA certified. This machine is excellent for:

Assembly of the detector is quick and easy and requires no tools; only hand tightening is required. The search coil connector must be clean, and the O-ring may require additional lubrication if it is dry upon assembly. The control housing is durable and lightweight and sealed with double O-rings to ensure electronics and battery components are safe from water damage. The control box consists of 3 buttons: Power, Elimination, and Threshold, along with a headphone plug. Power turns the detector on and off and allows users to choose a search mode. Elimination is used in conjunction with Standard or Discrete Trash Elimination modes to choose the proper elimination level for each users’ needs. 

As the knob is turned clockwise, more undesirable items are filtered out. It is best to keep the Elimination as low as possible for your search area to make sure you don’t miss anything. Threshold is used to set the base audio level according to each user’s needs.

The Sea Hunter Mark II has 2 search modes: Standard Trash Elimination and Discrete Trash Elimination. This metal detector is great at eliminating trashy targets. Standard is the typical mode found on most PI detectors. Background audio is continuous and stays near the chosen audio volume. 

Turning the Elimination knob clockwise allows the detector to find more types of metal. Standard mode requires a slow search coil sweep making it great for pinpointing. This will give the deepest detection and works best in areas with little trash. Garrett’s patented Discrete Trash Elimination mode makes the machine discriminate better than other PI machines. 

This helps filter out pull tabs, soda cans, and other undesirable targets. Background audio threshold will stay near the chosen volume, and targets will return with a sharp audio response. This mode is best used in areas with a lot of trash. 

The Sea Hunter Mark II excludes trash items from detection with almost no effect on targets with similar conductivity. This detector comes with enhanced discrimination mode and standard discrimination mode, allowing it to differentiate more precisely between targets. 

Switching on the Discrete Trash Elimination mode allows users to set the dial to eliminate pull tabs from detection, but will still show even thin gold rings, which alert very similarly to pull tabs. This makes it easier to zero in on valuable targets without digging a lot of trash targets. 

When searching underwater, the Sea Hunter Mark II can find ferrous and non-ferrous targets several feet below the soil and rock, even those items concealed in aquatic growth. Large items are easier to locate, and smaller items may be more difficult and require a comprehensive grid search. On land, if searching near a metal fence or building, Garrett recommends keeping the search coil parallel to the structure for best results.

Garrett recommends keeping Elimination as close to zero as possible until you determine the amount of trash metal in your search area. The search coil should be swung at a speed of approximately 1 to 2 feet per second, with a slight overlap in sweeping pattern. Audio increases will indicate the presence of metal under the search coil. 

When the Sea Hunter Mark II finds a target, to pinpoint, make an imaginary “X” over the target. The target will be where the sound is the loudest. Switching to Standard mode when pinpointing will allow you to hover over the target, since Discrete mode requires motion. Always recheck your target holes after removing your treasure to make sure nothing else remains.

The Sea Hunter Mark II is a heavier unit, as most PI metal detectors are, weighing in at 5.75 pounds. The unit can be hip mounted while on dry land to help absorb some of the weight and allow you to detect longer without using too much energy. The detector is adjustable from 28 inches to 52 inches. Ground balancing is preset on this metal detector and is not adjustable. It can operate in 2 modes: All Metal or Discriminate. The Sea Hunter Mark II features a microprocessor operating system and emits 750 pulses per second with 22 frequencies. This unit runs on 8 AA batteries giving users up to 22 hours of operation. Garrett recommends using a high-quality alkaline or nickel metal hydride batteries to avoid acid damage. 

Always remove the batteries prior to storage. If water enters the battery compartment, it should be rinsed with fresh water and allowed to air dry (after removing the batteries). The electronic compartment is factory sealed and will remain intact even if the battery compartment floods.

The Sea Hunter Mark II features an 8” PROformance round concentric search coil along with waterproof, fully submersible headphones. Be sure to wash off sand, salt, and residue off the detector immediately after use to avoid damage. 

Garrett offers a preventative maintenance program for a small fee where they will inspect the entire detector, replace seals, and pressure test the unit. The Sea Hunter Mark II is not designed for beginning detectorists but is a fantastic option for intermediate to advanced metal detectorists.

Garrett offers a 1-year warranty on the Sea Hunter Mark II. 

Pros:

  • Good price for a PI metal detector
  • 200-foot operating depth
  • Great choice for Scuba diving
  • Has been used by industry experts for years
  • Good battery life
  • Works well on land, on beaches, in saltwater, and in surf
  • Neutral buoyancy
  • Can find all types of metal
  • Discrete Trash Elimination
  • Multiple configurations
  • Hip mount
  • 750 pulses per second
  • 4 control housing mounting configurations
  • Easy assembly

Cons:

  • Heavy (5.7 lbs.)
  • Only 17 frequencies; other models have more
  • Only 1-year warranty

Garrett Sea Hunter vs Minelab Excalibur II

The Minelab Excalibur II is a VLF multi-frequency Broad Band Spectrum (BBS) technology underwater metal detector. This detector is waterproof up to 200 feet, like the Sea Hunter Mark II. BBS technology simultaneously transmits, receives, and analyzes an array of multiple frequencies to achieve substantial depth, high sensitivity, and great discrimination. The Excalibur II’s 17 frequencies range from 1.5 to 25.5 kHz. 

This broad range of frequencies provides the detector’s electronics with more target information and environmental information than a single frequency detector. This helps improve target identification and achieve greater depth. False signals due to high levels of ground minerals and saltwater are diminished with BBS technology. The Excalibur II comes with Minelab’s exclusive Iron Mask feature which ignores trash and provides a sharp and clear signal on good targets. 

The Excalibur II features a high visibility fluorescent design making it easy to see in murky waters. As with the Sea Hunter Mark II, this model can be hip mounted for use on dry land or in the surf. This detector has 2 search modes: Discriminate and All Metal. Discrimination and sensitivity can be adjusted to find your optimal settings. 

The Excalibur II can amplify weak target signals, reduce noise, and boost faint, deep object signals. This technology is called Receive Coil Boost (RCB) and it has 4 major advantages: 

  • Greater immunity to electromagnetic interference
  • Reduction of false readings
  • No lost signal strength
  • Improved detection sensitivity and depth

It also has a pinpoint setting to help zero in on targets more efficiently. 

The Excalibur II is easy to assemble, requiring no tools. This detector allows for 2 alternate configurations for the control box, whereas the Sea Hunter Mark II has 4 different configurations making it more versatile. It can be mounted traditionally, or side-mount upper shaft. Also, to get the different configuration, which is a side-mount upper shaft, an accessory must be purchased. This unit can also be hip mounted with an accessory. 

The Excalibur II has a 5-knob design: Discriminate, Sensitivity, Volume, Threshold, and Discriminate/Pinpoint/All Metals. Discrimination works on 17 different frequencies to filter out unwanted targets. 

As with any VLF metal detector, using the Excalibur II near sources of electromagnetic interference like powerlines, transmitters, electric fences, or cell phone towers may cause the detector to behave erratically and give numerous false signals. The detector may emit an overload sound, which is not harmful to the detector, and requires the user to move the coil away from any large metal objects or sources of electromagnetic interference. 

This detector is designed for experienced metal detectorists and divers, not for beginners. The Excalibur II is designed to find coins, relics, and jewelry. It comes with a 10” round Double-D hardwired coil and hardwired Koss 8-ohm headphones. This model does not have an LCD screen and utilizes knobs to function, as does the Sea Hunter Mark II. Ground balance can be done manually or automatic and it has a pinpoint mode to zero in on targets. A rechargeable battery pack is included, with an optional alkaline battery pack accessory, giving users 14 to 19 hours of use per charge. Audio alert signals low battery. The unit weighs 5.1 pounds. 

Minelab offers a 1-year warranty on this model.

Pros:

  • RCB technology
  • Iron Mask feature
  • Multiple frequencies
  • 200-foot operating depth
  • Fluorescent design
  • Pinpoint mode
  • Seamless operation in saltwater
  • Rechargeable battery pack with optional alkaline battery power
  • Hip mount option

Cons:

  • Only 1-year warranty
  • No LCD display (some may not like this feature)
  • Heavy for land use (5.1 lbs., slightly lighter than the Sea Hunter Mark II)
  • More Expensive than Sea Hunter Mark II

Garrett Sea Hunter vs Tesoro Sand Shark

The Tesoro Sand Shark (about $679 with 8” coil; roughly $709 with 10.5” coil) is a PI metal detector perfect for underwater treasure hunting. This detector combines PI technology with digital technology and created the first microprocessor-controlled PI metal detector. It is waterproof up to 200 feet. As with all PI detectors, this model works extremely well in saltwater and mineralized soil conditions. 

This model has 2 operating modes: Voltage Control Oscillator (VCO) and Normal. In VCO mode, as targets get near the coil, the threshold generates a louder and higher pitched tone. This mode works well for pinpointing. In Normal mode, a single tone is emitted and is best for beachcombing and other long searches. With the single tone in Normal mode, be prepared to dig every target so you don’t miss anything since there is no differentiation between target sounds.

Below, check out a video that directly compares the Garrett Sea Hunter to the Tesoro Sand Shark:

The microprocessor in the Sand Shark helps you customize the detector to your needs. This model contains a Pulse Width control allowing you to tune the detector to the perfect balance of sensitivity, depth, and battery life. This detector emits 600 pulses per second, lower than the Sea Hunter Mark II’s 750 pulses per second. The weight is lower on this model at just 4.5 pounds. It runs on 8 AA batteries, the same as the Sea Hunter Mark II, and is near neutral buoyancy. This model is not fluorescent colored, so it may be more difficult to see in murky or dark water conditions. The Sand Shark comes with hardwired headphones, unlike the Sea Hunter Mark II, which comes with plug in waterproof headphones. As with most PI machines, this metal detector is designed for more experienced detectorists. It does have a learning curve.

Assembly is easy for the Sand Shark and it requires no tools. The control housing can be configured in 4 different positions: under arm, under pole, diver’s setup, and body mount, similarly to the Sea Hunter Mark II. 

The manual shows these configurations in detail. These configurations make the Sand Shark a more versatile detector than the Excalibur II, and equally versatile as the Sea Hunter Mark II. Like the Garrett metal detector, Tesoro recommends using alkaline batteries to prevent acid damage to the control housing. Tesoro also recommends making sure the O-ring is dry and clean as water may damage the circuit board if allowed to encounter it. O-ring maintenance is mandatory for the warranty on this model.

All Tesoro metal detectors come with a lifetime warranty, which by far exceeds the warranty of any other metal detector on this list.  

Pros:

  • Lifetime warranty
  • Less Expensive than the Sea Hunter Mark II
  • Lighter weight than any other detector on this list
  • 200-foot operating depth
  • Pulse width control
  • Near neutral buoyancy

Cons:

  • Single tone audio target alert in Normal mode
  • Not fluorescent colored
  • Less pulses per second than Sea Hunter Mark II (600 pps vs 750 pps, respectively)
  • Normal mode only has 1 tone
  • Hardwired headphones so you can’t change to other headphones if you choose

Garrett Sea Hunter vs Garrett Infinium LS

The Garrett Infinium LS is a PI detector made from 2002 to 2015, replaced by the Garrett ATX (check out our in-depth review of the Garrett AT Max here). This model is still a great option for underwater metal detecting and is waterproof up to 200 feet. The Infinium was made with Garrett’s exclusive Advanced Pulse Induction (API) technology. 

As with all PI detectors, the Infinium LS does great in saltwater and highly mineralized soil conditions and can be used underwater, on beaches, and on land. It was designed to find relics, jewelry, and gold. As with the other PI detectors, the Infinium LS can be hip mounted to compensate for the weight of 5.5 pounds. It has adjustable audio threshold, and 96 adjustable frequencies, along with automatic ground balancing. Volume control can be used with land headphones. The Infinium has many more adjustable frequencies than the Sea Hunter Mark II.

Assembly is relatively easy on this model, and it requires no tools unless the cuff on the s-handle, which is factory installed, is loose or does not fit comfortably under the forearm. Then the nut, bolt, and washers should be loosened and removed to adjust the cuff. Like the Sea Hunter Mark II, the Infinium LS has 3 knob controls: Power, Threshold, and Discrimination. 

Turning on the unit, you can choose one of 3 Automatic Ground Tracking options: Slow, Lock, or Fast. Garrett recommends starting in Lock position until you know the conditions of your search area. Lock gives users the maximum depth detection unless the detector is not properly ground balanced or you are hunting in an area with changing ground mineralization that requires continuous ground tracking. 

Ground balancing is easy: simply set the Automatic Ground Tracking knob to Fast or Slow and bob the coil up and down. Discrimination should also be set low until you know the conditions of the search area.

Search modes on the Infinium LS include Motion and All Metal Deep Seeking with adjustable PI discrimination. It comes with a 10” PROformanceDouble-D search coil and land headphones. As with the Sea Hunter Mark II, the Infinium LS is near neutral buoyancy so it is easier to keep on the sea or lake floor. 

The Infinium LS generates 730 pulses per second, just slightly lower than the Sea Hunter Mark II’s 750 pulses per second. This model does not have an LCD screen and is controlled by knobs, like the Sea Hunter Mark II. The Infinium LS has 4 control housing configurations, like the Sea Hunter Mark II: hip mount, under the cuff, above or below the stem. 

The Garrett Infinium LS comes with a 2-year warranty (from some sellers).

Pros:

  • 730 pulses per second (Sea Hunter Mark II has 750; this one is closest to that)
  • 96 adjustable frequencies
  • Neutral buoyancy
  • 4 control housing configurations
  • 200-foot operating depth
  • Hip mount

Cons:

  • Model no longer in production, so it may be more difficult to find
  • More expensive than the Sea Hunter Mark II

Conclusion

Garrett’s Sea Hunter Mark II is one of the best underwater deep searching pulse induction metal detectors available today. Expert treasure diver and pioneer in scuba diving Sir Robert Marx and famous shipwreck diver Mel Fisher both trusted the Sea Hunter. 

Although each of the detectors in this article is a fantastic choice, the Sea Hunter Mark II remains my top recommendation. While there are models more expensive than the Sea Hunter Mark II with more features, for the price point, this detector cannot be beat. 

With advanced PI technology, 200-foot operating depth, and from a trusted name like Garrett, the Sea Hunter Mark II is a great purchase for anyone wanting to find underwater treasure and relics.

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