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Map of Monohansett Wreck (Thunder Bay National Marine Sanctuary)
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Boat entry

Monohansett Wreck (Thunder Bay National Marine Sanctuary)

Michigan, United States
Open Water suggested3–6 m (10–18 ft) depthBoat entry

Boat dive — see Entry & access.

Monohansett Wreck (Thunder Bay National Marine Sanctuary) at a glance

Monohansett Wreck (Thunder Bay National Marine Sanctuary) is a boat dive site in Michigan, United States with depths of 3–5.5 m (10–18 ft). Typically most favorable Jul · from 3 years of archive data. Divers commonly see Crayfish, Smallmouth bass, and Round goby. Check the latest conditions and entry details before you go.

Moderate window now· until 19:00 · sunset 18:29

Wind forecast for this hour · 16:00 · run 14 h ago
—

Tap a factor for its source and model point

Site hazards: Surface chop and boat/paddle traffic, sharp wreckage in shallow water, cold water

Read the full hazards ↓

Dive windows this week

Mon16:00–19:00 moderate

13 kn wind (13 kn wind)

Tue9:00–16:00 favorable, 16:00–17:00 moderate, 17:00–19:00 favorable

13 kn wind (13 kn wind)

Wed9:00–19:00 favorable

9 kn wind (9 kn wind)

Thu10:00–11:00 moderate, 12:00–15:00 moderate, 15:00–16:00 favorable, 16:00–18:00 moderate, 18:00–19:00 favorable

10 kn wind (10 kn wind)

Fri9:00–16:00 moderate, 16:00–19:00 favorable

13 kn wind (13 kn wind)

Sat9:00–19:00 favorable

5 kn wind (5 kn wind)

Sun9:00–19:00 favorable

5 kn wind (5 kn wind)

Favorable windowModerate window— no window

Every forecast dive window each day, site-local time, from wind forecasts. Numbers under each bar are daylight averages.

First light 7:33 · Sunrise 8:03 · Sunset 18:29 · some windows run past sunset

Source: Open-Meteo wind · updated 26 Oct, 01:24 GMT-4

Forecast only — always assess conditions on site.

Compare this weekend’s windows near Monohansett Wreck (Thunder Bay National Marine Sanctuary)

Forecast · NOAA tide model

Tide & slack timing

Loading tide predictions

Recent diver reports

Dated firsthand observations from divers — not current conditions.

No diver reports for this site yet. — one dated observation helps every diver after you.

Dived here today — did the forecast match?

What Divers Say

Known for: Crayfish, Smallmouth bass, Round goby
Best time: June-September on calm days; site is exposed to wind from most directions

Based on community reviews and site data. Conditions vary — always verify before diving.

Best months, historically

What conditions have historically been typical at this site, month by month — not a forecast.

  1. January, 12% of days have historically been favorable, wind has typically been 21 knots
  2. February, 11% of days have historically been favorable, wind has typically been 22 knots
  3. March, 6% of days have historically been favorable, wind has typically been 21 knots
  4. April, 14% of days have historically been favorable, wind has typically been 20 knots
  5. May, 32% of days have historically been favorable, wind has typically been 15 knots
  6. June, 31% of days have historically been favorable, wind has typically been 16 knots
  7. July, 43% of days have historically been favorable, wind has typically been 14 knots, historically most favorable
  8. August, 29% of days have historically been favorable, wind has typically been 16 knots
  9. September, 40% of days have historically been favorable, wind has typically been 15 knots
  10. October, 11% of days have historically been favorable, wind has typically been 20 knots
  11. November, 2% of days have historically been favorable, wind has typically been 23 knots
  12. December, 9% of days have historically been favorable, wind has typically been 22 knots

July has typically had the largest share of favorable days here. Conditions vary year to year — this is historical context, not a forecast.

Based on 3 years of archive data. Bar height shows the share of days each month whose conditions have historically scored favorably.

Marine life seen at this site

Species noted at this site — not a promise of what you’ll encounter.

Species seen here

Rough labels: “Commonly seen” usually means two or more recorded sightings near this site in public dive logs (GBIF), “Occasionally seen” one; “Seasonal” and “Rarely seen” come from dive-guide research. Not a measured rate.

Fills & rentals nearby

Facts from OpenStreetMap, corrected by the community — listed by distance only. Details change; confirm with the shop.

Shop facts come from OpenStreetMap and community corrections, shown nearest first. PickADive lists facts and contacts only — no listing is sponsored or ranked.

Data updated July 2026

Site details

The Monohansett was a wooden bulk freighter that caught fire and sank in the lee of Thunder Bay Island in November 1907 while sheltering from a Lake Huron storm. The wreckage lies broken into three large sections in only about 18 ft of clear water roughly 500 ft west of the Thunder Bay Island lighthouse, with the boiler reaching to within 10 ft of the surface and the propeller upright on the limestone bottom. Its shallow depth makes it popular with divers, snorkelers, paddlers and the local glass-bottom boat.

boatwreck

Surface chop and boat/paddle traffic, sharp wreckage in shallow water, cold water

Reviews

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