Fisher CZ-21 Dual Frequency Metal Detector for Underwater Hunting

The Fisher CZ-21, known to divers as the CZ21 QuickSilver, is a dual-frequency underwater metal detector submersible to 250 feet, built for scuba divers and surf hunters who work saltwater beaches, freshwater lakes, and deep dive sites. Where single-frequency VLF detectors chatter in hot black sand, wet salt, and mineralized mud, the CZ-21's Fourier Domain signal processing keeps targets clear. It ships with an 8-inch concentric waterproof coil, submersible headphones, manual ground balance, 3-tone audio target ID, and a removable control housing you can belt-mount for chest-deep surf or dives past the breakers. It is one of the underwater and waterproof metal detectors that professionals still rank at the top for saltwater work.

What's included

• Fisher CZ-21 detector with 8-inch concentric waterproof search coil
• Submersible headphones
• Two-year Fisher manufacturer warranty

Why divers and surf hunters choose the CZ-21

• Dual frequency that ignores salt. It transmits 5 kHz and 15 kHz at the same time and reads both through Fourier Domain processing, so wet salt does not false the machine the way it hammers single-frequency detectors.
• Submersible to 250 feet. Covers every surf zone and most recreational dive sites, with no depth anxiety.
• Manual ground balance for iron-heavy sites. Zeroes out soil minerals so you hear targets in trashy freshwater swim areas and old beach fills.
• Removable control housing. Detach the box, clip it to your belt or BC, and work the coil on an extended arm in current or tight spaces.
• Made in the USA. Engineered, assembled, and field-tested at Fisher's Texas facility for rugged reliability.

Where the CZ-21 performs best

Beach hunting and shallow water

The 250-foot rating covers all surf zone work and most dive sites. The control housing detaches from the shaft, so you can clip it to your belt and keep the coil on an extended arm when working waist-deep holes or around pier pilings. The 3-tone audio (low for iron, mid for foil and pull-tabs, high for coins and jewelry) runs through the submersible headphones, so you read targets by ear, not by staring at a screen in glare or murk.

Lake and river diving

Freshwater sites with iron trash, like old swim areas, sunken docks, and flooded homesteads, benefit from the manual ground balance and all-metal auto-tune mode. Ground balance zeroes out mineralization so you hear targets, not soil, and all-metal mode gives maximum depth on open sand flats and mud bottoms. The large-target alert boosts faint signals, which helps at depth and in low visibility.

Scuba and deep dive sites

Our team has taken the CZ-21 to 60 feet on wrecks and old ferry crossings. The dual frequency keeps working in high-conductivity saltwater without the drift you get from pulse induction machines that were not designed for discrimination. Touch-button controls and VCO no-motion pinpointing let you mark a target, set the detector on the bottom, and dig without losing the signal.

Fisher 1280X vs CZ-21

Both are submersible Fisher machines. Here is how they differ so you can choose.

Short version: the 1280X is a simpler, lower-cost submersible for surf and shallow water. The CZ-21 adds dual-frequency stability, 3-tone target ID, and manual ground balance for serious saltwater and dive hunting.

Specifications

• Operating Frequencies: 5 kHz and 15 kHz (dual frequency, simultaneous)
• Coil: 8" concentric waterproof search coil
• Waterproof Rating: Submersible to 250 ft
• Audio: 3-tone target ID (low, mid, high)
• Ground Balance: Manual
• Detect Modes: All-metal auto-tune, discrimination
• Pinpointing: VCO no-motion
• Control Housing: Removable for belt-mount
• Headphones: Submersible headphones included
• Country of Manufacture: USA (Texas)
• Warranty: Two years

Why buy from Serious Detecting

As an authorized Fisher dealer, every CZ-21 ships with a genuine two-year manufacturer warranty backed by Fisher's US support and service. Our team has run Fisher metal detectors in surf, lakes, and dive sites across the country, so we can walk you through coil choice, ground balance, and audio tuning for your conditions. Comparing machines in the $1,000 to $3,000 range? We will help you match the right tool to your sites. Free shipping, 30-day returns, and a price-match guarantee.