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Maritime Heritage Minnesota and its volunteers on May 30, 2019, pack the boat for a day on Lake Minnetonka looking for wrecks.

EXCELSIOR — A small boat is strategically packed with SCUBA gear — oxygen tanks line the stern — folding chairs, coolers and other bags of gear; some items shoved into every nook and cranny of the vessel.

It’s clear Ann Merriman and Christopher Olson of Maritime Heritage Minnesota have done this before. In fact, they’ve done this a lot, seeing as they’re the only two underwater archaeologists in Minnesota.

It’s just before 10 a.m. on May 30, 2019. Merriman and Olson, along with two volunteers, Kelly Nehowig and Mark Slick, and a Lakeshore Weekly News reporter are preparing to head out on Lake Minnetonka for the day to look for wrecks.


The result of the 2019 work was recently published as a Lake Minnetonka Nautical Archaeology report. (This report, and previous reports, are available at

That excursion last May was the first dive of the season.

At the time there was excitement among the Maritime Heritage Minnesota team — maybe over the fact Nehowig brought a container of cookies his wife baked, which are a favorite among the divers. Merriman jumped up and down when she saw them and made sure to carefully pack the container in the boat.

Maritime Heritage Minnesota will be spending this sunny day conducting underwater reconnaissance on anomalies that were previously captured on sonar imaging. Sonar is used to identify anomalies at the bottom of the lake, which might be human-made objects. Sometimes sonar signatures are obviously wrecks, but to answer specific questions about an anomaly, they’ll conduct SCUBA and sometimes use remote operated vehicles (ROVs) to collect hard data about the wreck or object.

Other anomalies don’t need to be dove upon because they can be identified “through their acoustical sonar signatures due to advancements in sonar technology” and compared to other anomalies that have already been identified and have similar signatures, Merriman said.

Their plan on this day is to focus on sonar anomalies in shallow water, hoping that since it is still so early in the season, weeds will not have yet covered up the site.

It was the first day of the diving season that would go on to include 35 dives, 17 days of targeted sonar scanning and two days of ROV work to confirm seven additional wrecks in Lake Minnetonka, identify several other anomalies as submerged cultural resources and do additional fieldwork on two previously discovered wrecks.

“All wrecks are significant no matter what they are made of, their condition and their age,” Merriman told Lakeshore Weekly News via email in January. “All sites and anomalies have and tell a story; some are more ‘interesting’ than others for a variety of reasons, but they are all significant and answer archaeological questions.”

MHM wreck - Steel Row Boat Wreck

Photo courtesy of Maritime Heritage Minnesota volunteers Kelly Nehowig and Mark Slick

The Steel Row Boat Wreck was confirmed in Lake Minnetonka on May 30, 2019.

Underwater reconnaissance

Once everything is securely packed in the boat, it’s off to dive on the first anomaly. Maritime Heritage Minnesota does not publicize where it finds wrecks or maritime sites in order to preserve the integrity of the historic sites.

Using GPS coordinates, they boat toward the anomaly. When they get close, Merriman launches a buoy with a diver flag near the site (sometimes it lands right on the site, other times divers have to swim a bit to get to the site), then they drop the anchor and prepare to jump in.

The preparation part takes time — there’s a lot of equipment and gear to check and put on. Only Olson, Nehowig and Slick are diving today, so Merriman helps them get their gear on. Nehowig and Slick are the videographers, armed with cameras, and jump in first to take video of the site before Olson gets in and stirs up the site, they said.

When they get enough footage, Olson, with a dive slate and measuring tape attached to his suit, begins his work, measuring and taking notes using a No. 2 pencil (they work “great” underwater, Merriman said). They’ll use this information, along with videos the volunteers capture, in their research to determine more information about the site.

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Ann Merriman, left, makes notes on a board before Christopher Olson, right, dives on a site. Olson will use a No. 2 pencil to write down the size and other characteristics of the site while underwater. They say No. 2 pencils write “great” under water.

Diving on anomalies is just one part of identifying wrecks at the bottom of the lake, and only a portion of their time is actually spent in the water. In fact, Merriman rarely gets in — she lets Olson and the volunteers do that because they like it — and instead stays on the boat, keeping a watchful eye on any approaching boats to make sure they don’t get within 150 feet (it’s the law) of the diver flags that are on the boat and on the buoy near the dive site. When they do, she is quick to yell “Divers below” until they move away.

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Ann Merriman of Maritime Heritage Minnesota launches the diver below buoy when they get to the site of an unidentified anomaly on Lake Minnetonka on May 30, 2019.

This scene plays out frequently, and Merriman’s frustration grows with each boat that gets too close, putting the divers at risk.

“Please, boaters, please be respectful of the diver down flag — it’s the law, but it’s common sense and the lake is busy enough without MHM and our volunteers having to fear for our safety,” Merriman told the newspaper. “The diver down flag does not mean that we are in trouble — it means we need you to stay away from us.”

Divers will spend anywhere from 10 to 30 minutes on a dive, depending on the depth and size of the site. After the divers have collected all the information they need, it’s time to get back on the boat.

“Getting in is easy,” Nehowig said. The hardest part is getting on the boat after a dive, the divers agreed.

On the first dive, they identified a wreck. After some discussion about the wreck, which was later identified as the Fiberglassed Plywood Outboard Wreck that likely sank around 1976, it’s off to the site of a vessel built in the mid-1950s at a location identified as the Triple Pontoon Boat Wreck Site.

MHM wreck - Triple Pontoon Boat Wreck

The Triple Pontoon Boat Wreck was confirmed in Lake Minnetonka during a dive on May 30, 2019.

In between the second and third dives of the day, the boat stops for a quick lunch — Merriman supplied Lunchables and soda to eat while sitting on the small folding chairs/stools they brought aboard — and then it’s back to identify more anomalies.

On this outing, they dove on more than five sites, confirming three wrecks and identifying a handful of other submerged sites. But their work isn’t complete.


Maritime Heritage Minnesota will use the information gathered during their fieldwork on May 30, and any subsequent outings, to conduct maritime historical research so Merriman and Olson can answer even more questions about the wrecks and anomalies, such as determining the wreck’s manufacturer, age, sinking date, etc., Merriman said. With some sites, they’ll fill out an archaeological site form to submit to the Minnesota Office of the State Archaeologist for a site number.

There are hundreds of remaining anomalies in Lake Minnetonka, and so long as there is grant funding and in-kind donations, Maritime Heritage Minnesota will continue to investigate the unknown anomalies in the lake until there are no more left to identify, Merriman said.

Melissa Turtinen is the community editor for Lakeshore Weekly News and Eden Prairie News. She's passionate about adding context to stories and informing people about what's going on in their community. She enjoys being outside, traveling and good beer.


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