NBM Dive Site Resource
SS Emperor
Isle Royale, Michigan, United States
TECHNICAL DIVE REQUIRED FOR THE DEEPER SECTIONS — SS Emperor spans approximately 25–155 ft / 8–47 m at Isle Royale. Its stern and other deep portions exceed recreational limits and require appropriate technical and decompression training.
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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.Published reference location
Location map
The marker shows the public coordinates associated with this profile. Confirm current access, moorings, and departure details before the dive.Map data © OpenStreetMap contributors
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 | 11.2°F / -11.6°C | 36.3°F / 2.4°C | No reliable record | — |
| Feb | 15.4°F / -9.2°C | 33.2°F / 0.7°C | No reliable record | — |
| Mar | 27.0°F / -2.8°C | 38.5°F / 3.6°C | No reliable record | — |
| Apr | 39.5°F / 4.2°C | 36.6°F / 2.6°C | No reliable record | — |
| May | 52.0°F / 11.1°C | 36.1°F / 2.3°C | No reliable record | — |
| Jun | 61.2°F / 16.2°C | 39.2°F / 4.0°C | No reliable record | — |
| Jul | 67.0°F / 19.4°C | 43.6°F / 6.4°C | No reliable record | — |
| Aug | 65.5°F / 18.6°C | 55.9°F / 13.3°C | No reliable record | — |
| Sep | 57.2°F / 14.0°C | 54.9°F / 12.7°C | No reliable record | — |
| Oct | 44.1°F / 6.7°C | 48.3°F / 9.1°C | No reliable record | — |
| Nov | 29.8°F / -1.2°C | 42.3°F / 5.7°C | No reliable record | — |
| Dec | 17.1°F / -8.3°C | 39.6°F / 4.2°C | No reliable record | — |
NOAA NCEI 1991–2020 U.S. Climate Normals — Duluth, MN
1991–2020 climate normalsReview source ↗NOAA NCEI Coastal Water Temperature Guide — Mid Superior
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
Basically intact 525-foot steel bulk freighter with bow damage; stern features include mast, rudder, propeller, engine room and cabins.
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
- Steel bulk freighter
- Vessel length
- 525 feet
- Wreck orientation
- Bow and stern sections at Canoe Rocks
- Present condition
- Basically intact; bow most damaged; stern retains major machinery and cabins
- Penetration guidance
- Deep and overhead sections require suitable training
- Protection or memorial status
- Isle Royale National Park
Plan the trip
Dive boats that visit this wreck
Superior Trips publishes this wreck in its Isle Royale inventory and describes Heyboy liveaboard trips that dive the island's major wrecks. Actual selection depends on weather, park rules, diver qualifications and trip profile.
Open boat profile →Grand Portage, MinnesotaDiscovery — Isle Royale and North Shore LiveaboardIsle Royale ChartersIsle Royale Charters explicitly publishes this wreck as a possible Discovery liveaboard destination; actual selection depends on weather, permits, diver qualifications and trip type.
Open boat profile →Regional context
Located within
Before you arrive
Access notes
Plan the dive for the intended section rather than treating the entire wreck as one depth. Isle Royale dive registration and park rules apply. The deeper stern area requires a technical gas and decompression plan; confirm mooring and operator conditions before departure. Published coordinates support regional discovery and are not a substitute for current navigation, active mooring information, operator guidance, permits, weather, or a dive plan.
Plan within your training
Conditions and hazards
Depth variation, possible decompression obligation, cold water, darkness, remote emergency response, entanglement, silt, confined passages and unstable wreck structure. Penetration requires separate wreck training.
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.