How to Use a Portable Metal Detector to Unearth Historical Coins and Merchant Relics on Coastal Shores

Last summer, I was trekking along a little-visited stretch of Monomoy National Wildlife Refuge beach on Cape Cod three hours after a nor'easter had blown through, my beat-up $120 portable metal detector slung over my shoulder, when the machine let out a sharp, high-pitched beep I'd never heard before. I knelt down, brushed away the top layer of wind-packed sand, and dug out a corroded but intact 1650s Spanish silver real---the kind of coin that circulated up and down the New England coast for 200 years, used by fishermen, traders, and even pirates to barter for supplies. That find was the first of dozens of historical coins, brass merchant tokens, and sailor's relics I've pulled out of coastal sand in the five years I've been detecting on shorelines, and it's a far cry from the lost earrings and soda cans most people associate with beach metal detecting.

Coastal shores are some of the most underrated spots for historical metal detecting, full of relics dropped by centuries of sailors, fishermen, traders, and shipwrecked passengers that have been churned up by tides and storms for generations. But detecting on saltwater beaches is nothing like hunting for lost change in a local park: salt, mineralized sand, shifting tides, and strict local rules mean you need to adjust your strategy, gear, and technique to make the most of your time---without damaging fragile coastal ecosystems or protected historical sites.

Pick the Right Portable Detector (No $1,000 Gear Required)

A lot of new detectorists think they need to drop a small fortune on high-end gear to find good coastal relics, but that's not true. You can get a perfectly capable portable detector for under $200 that will pull up historical finds just as well as a high-end model, as long as it has these three key features:

1. A waterproof search coil: Non-negotiable. You'll be wading through shallow surf, walking through wet sand at low tide, and even digging in waterlogged spots, so a non-waterproof coil will short out the second it gets wet. Most mid-range portable detectors come with an optional waterproof coil for under $50, and it's worth every penny.
2. Saltwater mode and adjustable ground balance: Coastal sand is loaded with iron oxide and salt, which causes constant false signals if your detector can't adjust for mineralized soil. Look for a model with a dedicated saltwater setting and manual ground balance adjustment, so you can tune out the "noise" from the sand and only pick up signals from actual metal targets.
3. Lightweight, portable design: You'll be walking for miles along the shore, so a heavy detector will leave your arm sore after an hour. I use a mid-range Garrett Ace 250 with a 7-inch waterproof coil that weighs less than 3 pounds, and it's perfect for all-day trips without arm fatigue.

Skip the fancy GPS and large-screen models if you're just starting out---they're bulky, expensive, and unnecessary for coastal detecting, where most of your finds will be within a foot of the surface anyway.

Pre-Trip Prep That Saves You Hours of Wasted Time

Before you even step foot on the sand, do two hours of research to avoid showing up to a spot where detecting is banned, or where there's nothing to find: First, check local rules. Many coastal beaches, especially wildlife refuges, state parks, and sea turtle nesting grounds, ban metal detecting entirely, or only allow it in designated zones. Some areas require a free permit for recreational detecting, and all historical finds over 50 years old are often required to be reported to local authorities. Don't skip this step---fines for illegal detecting on protected land can run into hundreds of dollars, and you could be banned from the area entirely.

Second, research the spot's history. The best coastal detecting spots are near 17th-19th century fishing villages, old trading posts, or documented shipwreck sites. Old nautical charts, local historical society records, and even old newspaper archives (search for "shipwreck" + the name of the beach) will give you a list of spots where ships ran aground, or where fishermen dumped trash and lost supplies over the centuries. The stretch of beach I found that Spanish real? It's right off the site of a 17th century fishing outpost that was abandoned in 1750 after a series of winter storms washed most of the buildings into the ocean.

Third, check tide charts. The best time to detect is 1-2 hours before low tide, when you have the maximum amount of exposed sand, and the tide has had time to churn up new buried relics. Never go detecting during high tide, when the water covers most of the sand, and always set a timer on your phone so you don't get caught by the incoming tide---coastal tides can come in faster than you expect, especially on beaches with steep drop-offs.

Master the Coastal Detecting Technique Most Beginners Skip

Once you're on the beach, follow these steps to avoid missing targets and digging up 100 bottle caps a day:

1. Ground balance first, then every 30 minutes. Walk to a patch of sand with no obvious metal debris, hold your search coil 2 inches off the ground, and adjust the ground balance setting until the constant beeping from mineralized sand stops. Do this every 30 minutes as you move along the shore, because sand composition changes drastically between the dunes, the high-tide line, and the shallow surf. Skipping this step is the number one reason beginners get frustrated with coastal detecting---they spend all day digging up trash because they didn't tune out the sand's false signals.
2. Sweep the coil low and slow. Keep your coil 1-2 inches off the sand at all times, and swing it side to side in slow, overlapping arcs---each new sweep should overlap the last one by 50% to avoid missing small targets. Most new detectorists swing the coil too fast or too high, which makes them miss small coins and tiny merchant tokens that are buried under just an inch of sand.
3. Focus on the high-tide line first. This is the line of wet sand left by the last high tide, and it's where waves deposit new churned-up sand and relics every day. Most of your best finds will be right along this line, especially after a storm. Once you've covered the high-tide line, move down to the low-tide line, and if you have a waterproof detector and coil, wade into the shallow surf (up to your ankles, never higher, for safety) to sweep the sand just below the water surface---this is where shipwreck debris and old fishing gear often gets trapped.
4. Use discrimination to filter out trash. Most modern detectors have a discrimination setting that lets you ignore signals from iron and aluminum, so you only get beeps for brass, copper, silver, and gold---the materials most historical coins and merchant relics are made of. Turn the discrimination up just high enough to ignore bottle caps and nails, but not so high that you miss low-grade copper coins, which are some of the most common historical finds on coastal shores.

Dig Smart to Protect the Beach (And Your Finds)

When your detector beeps, don't just dig a big 6-inch hole with a shovel---that tears up dune grass, disturbs nesting sea turtles, and leaves big holes that other beachgoers can trip in. Instead:

• Use a small hand trowel or even a heavy-duty plastic knife to dig a small, round plug of sand, no bigger than the size of your fist.
• Brush away the sand with your hand, or sift it through a small handheld mesh sieve (the kind used for gold panning works perfectly) to find small targets that are buried under the surface. I once found a tiny 1790s copper half-penny buried under 2 inches of sand that I would have missed completely if I hadn't sifted the dirt I dug up.
• Never use harsh chemicals or wire brushes to clean corroded coins or relics. This ruins the historical patina and can damage the object beyond repair. Rinse it gently with fresh water, let it air dry, and if you're not sure what it is, reach out to a local historical society or numismatist to help you identify it.

The Most Common Coastal Historical Finds (And What They Mean)

You don't need to find a chest of Spanish gold to make a coastal detecting trip worth it. The most common historical finds on Atlantic and Pacific coast shores include:

• Spanish silver reals and copper coins from 16th-18th century shipwrecks, which circulated as currency along the coast for centuries. Most are worth $10-$50, but rare dates or mint marks can fetch hundreds.
• Colonial American copper pennies and half-pennies, often dropped by fishermen or traders in the 1700s and 1800s. Most are worth $5-$20.
• 19th century brass merchant tokens, used by fishing companies and general stores to pay workers before cash was widely available. Tokens with clear company names or logos can be worth $20-$100 to local collectors.
• Clay pipe stems, which were discarded by sailors after use from the 1600s to the 1800s. Most are worth less than $5, but if you find one with a clear maker's mark or date, it's a cool piece of history to add to your collection.
• Small brass ship fittings, like nails, hinges, or compass parts, often from small fishing vessels that sank in shallow water. Most are worth $5-$15, but they make great display pieces.

My best find to date isn't a rare coin, though: it's a tiny brass token from a 1820s Gloucester fishing company, stamped with the name of the schooner my great-great-grandfather worked on as a deck hand. It was buried under an inch of sand right at the high-tide line, and I almost skipped it because the signal was so faint. But that's the thing about coastal metal detecting: the best finds aren't the shiny gold coins or rare relics you see in movies. They're the small, quiet connections to the people who lived and worked on these shores long before us, waiting to be pulled out of the sand by someone patient enough to look.

Non-Negotiable Rules for Ethical Coastal Detecting

Before you head out, keep these rules in mind to protect both the coast and its history:

1. Never detect in protected areas: wildlife refuges, sea turtle nesting grounds, and designated historic sites are off-limits, and detecting there can result in heavy fines.
2. Report significant historical finds: If you find a large number of relics from the same site, or an intact artifact that looks like it's part of a shipwreck or old settlement, don't remove it. Report it to local park rangers or the historical society, so they can document the site before it's lost to erosion.
3. Fill in all your holes after you dig, and pack out any trash you find---don't leave broken glass or plastic in the sand, it can hurt wildlife and other beachgoers.
4. Don't post exact locations of good detecting spots on social media. Overcrowding from detectorists has led to many beaches banning detecting entirely, so keep your favorite spots quiet to protect them for other people to enjoy.