People tend to ask what you can find or see underwater, and my response is “pretty much anything!” In a quarry down by Tenants Harbor, we have come across washing machines, BBQ grills, lawn mowers and even a car! I can tell you I was a little nervous to take a peek into that trunk! More on that site later!

This sunken car was found at the Long Cove Quarry in St. George Photo by Charles H. Lagerbom

To assist with the process of searching for something underwater, some divers go with an underwater metal detector. There are two types of metal detectors, VLFs and PIs. Very Low Frequency detectors are cheaper but tend to disappoint in mineralized sands and soils. Many also cannot go underwater, especially salt water.

The other kind is a PI detector or Pulse Induction. More expensive, they tend to detect deeper than VLFs, can be submerged up to 200 feet in ocean water and work way better in mineralized sands and soils that many VLFs struggle with.

Intrigued with the idea of searching for things under the sea, a few years back I bought a Garrett Sea Hunter Mark II metal detector. It is a PI and pretty cool to use; I even rigged up a GoPro mount on it so I could capture video during searches. It comes with underwater headphones; yes, you wear them over your hood or beanie while diving.

Lagerbom uses underwater headphones with his Garrett Mark II detector. Photo by Charles. H. Lagerbom

What I like about the Mark II is that it is pretty rugged and can also be used on land and on the shore, all three metal detecting environments. And it is all about the beeps. Everything it encounters is interpreted by audio, there are no digital displays or screens. This is good when there is low or no visibility — you just rely on your ears.

Pulse Induction works by sending high amperage signals through a copper coil, creating an electromagnetic field. This field then collapses, which in turn creates a voltage spike easily picked up by the coil if something metallic is encountered. This results in a “hit” and an audio beep.

While there are two crude trash elimination mode settings on the Mark II, it does take some time to learn to discriminate the different pulses or hits or beeps that you get. Bits of metal, iron nails, copper coins, silver rings and gold doubloons all give off slightly different beeps. I am not all that proficient with it yet, so for me, any beep means something is there, let’s dig for it! More adept users can be more discriminating, that just comes with time and experience.

In addition to looking for pirate gold, you can also use underwater metal detectors for search and recovery efforts. Most of my search jobs have been successful using visual, circular search patterns mostly with a reel and an anchor chain. That is how I recovered a hunting rifle and backpack that were lost when a hunter flipped his canoe in a pond. More on search and recovery later!

My dive buddy, Sean, however, has used his metal detector with great success in finding wicked small things like rings. In fact, he has kind of become the “ring-finder” for the area, the go-to guy for that lost one-of-a-kind item. He often gets calls from frantic clients, some as far away as New Hampshire.

He tells me there is a strong urge by the owner to find that lost ring, mostly due to its sentimental value. They are therefore willing to pay for time, mileage, and other costs, which can add up significantly. But the need to find that wedding, or engagement, or class, or family heirloom ring lost at the beach or while swimming tends to rationalize any costs. I find that pretty interesting.

Plus, a ring can be pretty difficult to find underwater, especially with the challenge of what we call “memory location.” This tends to be the spot indicated where the owner knows “just exactly” where the item should be. Oh yeah…it’s right there, I know it! Right there!

Hint: It is rarely, if ever, where they think it is! As a result, searchers pretty much assume they will be looking over a large area, which is why you usually bring at least two tanks of air on searches like this.

On a foggy morning at Searsport, visibility underwater was still good. Photo by Charles. H. Lagerbom

The bottom terrain is also important. Even with muck, small items tend to land on top of it. The problem is that they usually get ground down into it by those who looked immediately after the initial loss. The area gets churned over pretty easily. Sean tells the people to stay away from the area until he can get there; otherwise the ring could simply get trampled deeper into the bottom.

The large metal detector provides an initial beep, but then Sean goes to work with a hand-held wand or pin pointer which vibrates when over the metallic object. The more popular the location, obviously means the more stuff that is likely to be found, such as coins, cans, pull-tabs, and other assorted metal trash. This has the effect of slowing down the search while all this stuff is encountered.

Rocky bottoms are also difficult. A ring can easily slip between cracks or down into crevices that even the best metal detectors cannot locate. Grass and weeds are another tricky bottom form to search. By far, the best bottom terrain is sandy, but you get what you get when called for a job.

You also need good buoyancy control skills so that you yourself do not crash into the bottom or brush it with your hand or a fin. Any decent visibility will quickly disappear, so take care to hover over the area. This skill is developed over time.

But the gratitude and relief of returning a lost item to its owner is pretty cool. Sean says he has been afterwards invited to weddings and sometimes gets Christmas cards from appreciative clients. I like the sense of having found something for someone, especially something of a challenging size or in challenging conditions.

A search job for a specific lost item tends to be over a defined area. This is different when Sean and I just go dive detecting; then there is usually no clear route or path. We might just want to see what is out there beyond a swimming area, or off a dock or in a high traffic area where someone might have dropped or lost something.

We tend to work those areas in a methodical, casual way. Sometimes that is difficult with limited visibility or currents or boat traffic or other factors. Sean and I usually putter along, one of us occasionally stopping with a hit for further investigation. A search like this also allows us to come across non-metallic items of historical interest such as ceramics, bricks, clay pipe pieces, glass items and other treasures.

Working in tandem, divers poke along on a general search pattern. Photo by Charles H. Lagerbom

With a good, strong hit, I’ll grab the trowel clipped to my harness and get to digging. Problem is that visibility quickly goes to nothing once digging starts. The metal detector has a strap to wrap around your wrist, so that you don’t put it down somewhere or let it drift away. You can probably see how all this gets challenging with lots of things to handle and keep track of, just to dig into the muck for something!

But it is all worth it if you uncover something that has not been seen for some time. Coming across a colonial clay pipe or a silver spoon or a lead musket ball makes the search well worth it!

Some places we have detected include Beauchamp Point in Rockport, Duck Trap Harbor, and the Rockland Breakwater. We have gone a couple of times to Searsport and poked along the cove between Mossman Park and the old Hamilton Marine building on Route 1. One foggy morning, I thought the dive there was going to be a bust, but visibility underwater proved decent. Coolest thing I found that day was a bronze ship spike..

This bronze ship spike was found off Mossman Park in Searsport. Photo by Charles H. Lagerbom

But you need to be careful. One thing about underwater metal detectors is that handling one means yet one more task added to what you are responsible for while diving. This could lead to the danger known as “task overloading.” Too many things to keep track of, pay attention to or handle can become overwhelming and quickly turn into a problem.

One hand with the detector usually means your other hand is using a trowel to do the digging. Then you also have a net bag or something within easy access on you to put the item in if it is worth keeping — all the while maintaining good buoyancy in the water column.

Sweeping coil in an arc pattern, one can cover a lot of terrain. Photo by Charles H. Lagerbom

So, there are lots of things going on, in addition to your regular dive awareness and duties, which is why I decided to mount my GoPro on the detector rather than have yet one more thing in my hands while doing all this.

The result is a pretty cool hobby and some interesting historical finds, whether I am poking along an old cellar hole on a friend’s farm, sweeping the beach at Belfast City Park or searching the bottom terrain in 25 feet of seawater in search of pirate treasure. If it is out there, I am hoping to find it!

Charles Lagerbom teaches AP U.S. History at Belfast Area High School and lives in Northport. He is author of “Whaling in Maine” and “Maine to Cape Horn,” available through

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