A three-dimensional point cloud model of the shipwreck "Senator" resting on the seafloor, rendered with colored points ranging from green for the seabed and lower parts of the hull to yellow and orange for the upper deck and structures. The data visualization shows the vessel's form and the surrounding underwater terrain against a dark background.

Exploring Wisconsin Shipwreck Coast National Marine Sanctuary at Scale

Past Expedition

Primary Goal

Explore and document a collection of nationally significant shipwrecks in the deep waters (130-480 feet) of Lake Michigan’s Wisconsin Shipwreck Coast National Marine Sanctuary

Dates

August 2-12, 2025

Location

Great Lakes; Wisconsin Shipwreck Coast National Marine Sanctuary

Vessel

Research Vessel Laurentian

Primary Technology

Hybrid autonomous underwater vehicle/remotely operated vehicle, sonar

Overview

In August 2025, a team of maritime archaeologists and engineers conducted fieldwork in Lake Michigan’s Wisconsin Shipwreck Coast Marine National Sanctuary. Their goal was to test new technology and techniques for exploring deepwater shipwrecks — and learn more about our past. They focused on two known historically significant shipwrecks, collecting more detailed imagery of the wrecks than ever before and gaining a better understanding of how they met their fates and their conditions today.

A yellow underwater vehicle partially submerged in blue ocean water with antennas and sensors visible.

The Saab Sabertooth hybrid autonomous underwater vehicle/remotely operated vehicle (AUV/ROV) during fieldwork for the Exploring Wisconsin Shipwreck Coast National Marine Sanctuary at Scale project. Hybrid vehicles like this one are capable of working in deep water either autonomously or via a tether. Image courtesy of Exploring Wisconsin Shipwreck Coast National Marine Sanctuary at Scale. Download largest version (jpg, 2 MB).

Three men wearing hard hats and orange life vests, one of which reads "NOAA GREAT LAKES," are securing a large, yellow "SABERTOOTH" autonomous underwater vehicle on a metal frame aboard a boat deck under bright sunlight.

Recovering the Saab Sabertooth hybrid autonomous underwater vehicle/remotely operated vehicle (AUV/ROV) at the end of the day during the fieldwork of the Exploring Wisconsin Shipwreck Coast National Marine Sanctuary at Scale project. Image courtesy of Exploring Wisconsin Shipwreck Coast National Marine Sanctuary at Scale. Download largest version (jpg, 2 MB).

Maritime Heritage in the Great Lakes

Canal schooner Walter B. Allen. In April 1880, after a career of carrying grain and coal across the Great Lakes, Walter B. Allen ran ashore on South Manitou Island in Lake Michigan during a gale and sank to the bottom of the lake during recovery efforts. Today, it sits upright in 160 feet of water. Because the cold freshwater of the Great Lakes preserves wrecks remarkably well, the lakes offer some of the best conditions in the world for studying historic shipwrecks. Image courtesy of Becky Kagan Schott. Download largest version (jpg, 1 MB).

The Great Lakes and their connecting waterways form a natural corridor stretching over 1,000 miles into the heart of North America. For more than 10,000 years, people have used these inland seas for communication, food, exploration, settlement, and trade. An estimated 6,000 shipwrecks lie beneath the surface of the five lakes, including 1,200 in Lake Michigan alone—many still waiting to be discovered and explored.

Shipwreck Exploration

An introduction to the fieldwork operations for the Exploring Wisconsin Shipwreck Coast National Marine Sanctuary at Scale project. Video courtesy of Dale Pelecek. Download HD version (mp4, 135.7 MB)

Due to rough weather and technical glitches, the team adapted their original plan to explore a number of nationally significant shipwreck sites, focusing instead on collecting more detailed data at two of them: the schooner Northerner and the steamer Senator. Both had been explored before, but this time they used a hybrid autonomous underwater vehicle/remotely operated vehicle (AUV/ROV) equipped with acoustic, imaging, and laser scanning sensors — the same digital stills camera/laser system recently used to map and model Titanic. Along with new archaeological methods developed to capitalize on the efficiencies of autonomous and uncrewed vehicles, the team was able to collect large amounts of data in a short amount of time.

A map shows a portion of the Wisconsin coastline and Lake Michigan, with towns like Port Washington and Knellsville visible. A red line outlines the "WSCNMS Boundary" within the lake. Green diamonds mark "Sites Documented," including "Northerner" closer to the shore and "Senator" further out. An inset map in the lower left corner shows a larger section of the coastline with a yellow box indicating the area of the main map. A scale bar in the lower right indicates distances in miles.

Map showing the locations of the shipwrecks explored and documented in August 2025 during the Exploring Wisconsin Shipwreck Coast National Marine Sanctuary at Scale project and their context within the boundaries of the sanctuary. Image courtesy of Exploring Wisconsin Shipwreck Coast National Marine Sanctuary at Scale. Download largest version (jpg, 564 KB).

A man with gray hair and a beard leans over a metal desk in a cluttered workspace, looking intently at a laptop screen showing a blue underwater image. Another open laptop to his right displays black and white sonar data. Multiple monitors, keyboards, and wires are visible around the equipment.

Russ Green, superintendent of Wisconsin Shipwreck Coast National Marine Sanctuary, looks over data gathered at the Northerner wreck site during fieldwork for the Exploring Wisconsin Shipwreck Coast National Marine Sanctuary at Scale project. Built in 1850, Northerner filled with water, capsized, and sank with a cargo of cordwood in its hold while being towed to Milwaukee for repairs in 1868. Today it rests upright on the lake floor, 135 feet below the surface of Lake Michigan. Image courtesy of Exploring Wisconsin Shipwreck Coast National Marine Sanctuary at Scale. Data from Hibbard Inshore. Download largest version (jpg, 2 MB).

A woman with braided hair points to a laptop screen showing sonar data, while a bearded man types on the keyboard in a cluttered workspace with a "DEVICE LITHIUM BATTERY CHARGING AREA" sign visible in the background.

Caitlin Zant, research and communications specialist of Wisconsin Shipwreck Coast National Marine Sanctuary, and Brad Hibbard, president and chief applications engineer of Hibbard Inshore, discuss the plan of operations to document the steamer Senator during the fieldwork of the Exploring Wisconsin Shipwreck Coast National Marine Sanctuary at Scale project. Image courtesy of Exploring Wisconsin Shipwreck Coast National Marine Sanctuary at Scale. Download largest version (jpg, 2 MB).

Following two dives to ensure the technologies were working as expected, the team deployed the AUV/ROV to a depth of 41 meters (130 feet) for a test dive at the Northerner site. There, they investigated parts of the ship’s rigging that have not been documented in over a decade. Their distance from the main wreck could help explain how the ship broke apart.

An overhead photomosaic shows the wooden shipwreck "Northerner" resting on the seafloor. The vessel's deck planks, hatches, and a broken mast stubs are visible, showing the ship's long, narrow form. The image is composed of many smaller photos stitched together, creating a detailed view against a dark, textured seabed with irregular edges.

Detailed photomosaic of Northerner. In just over an hour of dive time, the Saab Sabertooth hybrid autonomous underwater vehicle/remotely operated vehicle (AUV/ROV), with its powerful lights to help image the wreck, captured hundreds of high-resolution still images to produce a 3D model. Explore the Northerner model in depth in the NOAA Ocean Exploration Photogrammetry Collection or download the photomosaic here and zoom in to examine it more closely. Image courtesy of Hibbard Inshore. Download largest version (jpg, 2 MB).

During five dives at the Senator site, which ranged in depth from 90 to 125 meters (300-420 feet), they collected data and imagery — including the first sonar-based 3D pictures of the site — that helped them understand the wreck as a whole. In particular, it helped them understand how Senator sank and settled on the lake floor, find additional artifacts and wreckage located far away from the main wreck site, and learn more about the lake floor itself.

An initial perspective point cloud model of Senator made with data collected by the laser scanner on the hybrid autonomous underwater vehicle/remotely operated vehicle during the fieldwork of the Exploring Wisconsin Shipwreck Coast National Marine Sanctuary at Scale project. Senator is a 400-foot long steamer built in 1896 that went down with its cargo — 268 Wisconsin-built Nash automobiles — in 1929 after it was hit by another vessel. It now rests in 415 feet of water and is the deepest known wreck in the sanctuary. Image courtesy of Hibbard Inshore. Download largest version (jpg, 2 MB).

Advancing History, Resource Protection, and Exploration

The data and imagery collected have already given the team new insight into the wrecks, but there’s more to come. They’re still processing the high-resolution data to finalize the 3D and point cloud models of both wrecks, which will be some of the clearest imagery available of Northerner and Senator.

There’s much more to explore and learn, and the team will head out again in summer 2026 to continue their work by exploring more and deeper sites.

Ultimately, this project will help the sanctuary and Wisconsin State Historic Preservation Office monitor and preserve these wrecks and contribute to the understanding of the role of the Great Lakes in our nation’s maritime heritage. In addition, the team’s new techniques for exploring deepwater shipwrecks will advance the field of marine archaeology by accelerating the exploration, documentation, and management of maritime heritage sites.