NBM Dive Site Resource
Straits of Mackinac
Chicago, Illinois, United States
A former car-and-passenger ferry intentionally sunk as a Lake Michigan artificial reef, with the wreck reaching recreational depths from its mast to the sand.
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Historic Photograph
Aquatic life at this dive site
What divers may encounter
Three reviewed connections are featured here. Sightings vary by season, conditions, and chance, so they are never guaranteed.
Aquatic life research in progress
NBM is reviewing a likely local species for this position.
Aquatic life research in progress
NBM is reviewing a likely local species for this position.
Aquatic life research in progress
NBM is reviewing a likely local species for this position.
Site media
Photographs
Three views rotate from the published gallery on each visit.
Contributor media
Dive videos
Three featured video positions are reserved on every profile.Recent field observations
Diver-reported temperatures
Automatically checked observations from dives during the past 14 days. Three reports are visible at a time; scroll for more.A report that passes the automatic checks will appear here with the dive date, diver’s display name, and temperatures at each depth.
Reports are automatically checked for plausible dates, depths, and temperatures. They are observations, not forecasts; confirm conditions before diving.
Seasonal planning reference
Typical monthly conditions
Long-term averages, not a forecast. Actual air and water conditions can change quickly and may vary across the site.Moderate-confidence match — Matched by documented Great Lakes port/area. Air and surface-water values are regional planning averages. No bottom-water line is published because a comparable depth-specific record has not yet been verified.
| Month | Average air | Surface water | Bottom water | Bottom measurement depth |
|---|---|---|---|---|
| Jan | 25.2°F / -3.8°C | 35.2°F / 1.8°C | No reliable record | — |
| Feb | 28.8°F / -1.8°C | 36.6°F / 2.6°C | No reliable record | — |
| Mar | 39.0°F / 3.9°C | 37.8°F / 3.2°C | No reliable record | — |
| Apr | 49.7°F / 9.8°C | 38.3°F / 3.5°C | No reliable record | — |
| May | 60.6°F / 15.9°C | 42.5°F / 5.8°C | No reliable record | — |
| Jun | 70.6°F / 21.4°C | 53.7°F / 12.1°C | No reliable record | — |
| Jul | 75.4°F / 24.1°C | 68.2°F / 20.1°C | No reliable record | — |
| Aug | 73.8°F / 23.2°C | 72.2°F / 22.3°C | No reliable record | — |
| Sep | 66.3°F / 19.1°C | 68.4°F / 20.2°C | No reliable record | — |
| Oct | 54.0°F / 12.2°C | 58.5°F / 14.7°C | No reliable record | — |
| Nov | 41.3°F / 5.2°C | 49.0°F / 9.4°C | No reliable record | — |
| Dec | 30.5°F / -0.8°C | 43.7°F / 6.5°C | No reliable record | — |
NOAA NCEI 1991–2020 U.S. Climate Normals — Chicago O’Hare, IL
1991–2020 climate normalsReview source ↗NOAA NCEI Coastal Water Temperature Guide — Station 45007
Historical monthly station averagesReview source ↗Bottom temperature is never inferred from surface temperature. A blank month means no reliable depth-specific average is available. Data reviewed 2026-08-26.
Why divers know this place
Highlights
Large 204-foot ferry artificial reef with vertical relief from about 45 to 82 feet.
Shipwreck-only module
The wreck
This section appears only on shipwreck records and brings the vessel, its loss, present condition, access, and responsible wreck-diving considerations into one place.
- Vessel type
- Car and passenger ferry
- Year sunk
- 2003
- Vessel length
- 204 ft
- Cause of loss
- Intentionally sunk as an artificial reef
- Wreck orientation
- Upright
- Present condition
- Purpose-sunk and accessible; mast rises to roughly 45 feet
- Penetration guidance
- Large interior spaces remain overhead environments requiring training
History and significance
The ferry carried vehicles and passengers across the Straits of Mackinac before the Mackinac Bridge opened, then began a second life as an artificial reef.
Before you arrive
Access notes
Confirm the selected wreck, departure, current conditions, mooring status and diver requirements directly with the operator.
Plan within your training
Conditions and hazards
Cold water, changing visibility, boat traffic, entanglement and fragile or unstable wreck structure. Depth-specific decompression and overhead hazards may apply.
Independent resource notice
This record is a starting point for independent verification. Access, closures, moorings, weather, currents, depth, visibility, operator availability, and site conditions can change without notice. Confirm current information with the responsible operator, property owner, managing authority, or another qualified local source before planning or attempting a dive.