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Map of Hennepin Wreck
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ExpertBoat entry

Hennepin Wreck

Michigan, United States
Extreme depth (230 ft)70 m (230 ft) depthBoat entry

Boat dive — see Entry & access.

Hennepin Wreck at a glance

Hennepin Wreck is an expert boat dive site in Michigan, United States with depths of up to 70 m (230 ft). Typically most favorable Jul · from 3 years of archive data. Divers commonly see Quagga mussel and Burbot. Check the latest conditions and entry details before you go.

Favorable window now· until 10:00, then favorable & moderate until 19:00 · sunset 18:48

Wind forecast for this hour · 9:00 · run 7 h ago
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Tap a factor for its source and model point

Site hazards: Extreme depth (230 ft) · Severe cold and darkness at depth · Long offshore boat ride in open Lake Michigan

All 4 hazards ↓

Dive windows this week

Mon9:00–10:00 favorable, 10:00–16:00 moderate, 16:00–19:00 favorable

15 kn wind (15 kn wind)

Tue9:00–15:00 moderate, 15:00–19:00 favorable

14 kn wind (14 kn wind)

Wed9:00–17:00 favorable, 17:00–19:00 moderate

12 kn wind (12 kn wind)

Thu14:00–16:00 moderate, 16:00–17:00 favorable, 17:00–18:00 moderate, 18:00–19:00 favorable

14 kn wind (14 kn wind)

Fri9:00–15:00 favorable, 15:00–19:00 moderate

13 kn wind (13 kn wind)

Sat9:00–19:00 favorable

7 kn wind (7 kn wind)

Sun9:00–19:00 favorable

7 kn wind (7 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 7:44 · Sunrise 8:13 · Sunset 18:48 · some windows run past sunset

Source: Open-Meteo wind · updated 26 Oct, 01:25 GMT-4

Forecast only — always assess conditions on site.

Compare this weekend’s windows near Hennepin Wreck

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

Best time: Mid-summer (June-September) on flat-calm days only, given the offshore distance.

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 20 knots
  2. February, 14% of days have historically been favorable, wind has typically been 20 knots
  3. March, 11% of days have historically been favorable, wind has typically been 20 knots
  4. April, 22% of days have historically been favorable, wind has typically been 18 knots
  5. May, 37% of days have historically been favorable, wind has typically been 16 knots
  6. June, 36% of days have historically been favorable, wind has typically been 15 knots
  7. July, 56% of days have historically been favorable, wind has typically been 14 knots, historically most favorable
  8. August, 44% of days have historically been favorable, wind has typically been 15 knots
  9. September, 51% of days have historically been favorable, wind has typically been 14 knots
  10. October, 17% of days have historically been favorable, wind has typically been 19 knots
  11. November, 9% of days have historically been favorable, wind has typically been 21 knots
  12. December, 10% of days have historically been favorable, wind has typically been 21 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

No dive shops mapped within 25 km (16 mi). Know one? Add it to the map.

Data updated June 2026

Site details

The Hennepin, built 1888 and converted in 1902 into the world's first self-unloading bulk carrier, foundered on August 18, 1927 about 15-20 miles off South Haven; her entire conveyor and A-frame unloading system is still in place. Located by Michigan Shipwreck Research Associates in 2006, she sits upright in about 230 ft of Lake Michigan within the Southwest Michigan Underwater Preserve. This is a serious trimix technical dive — cold, dark, and far offshore — but historically one of the most important wrecks in the Great Lakes.

boatwreck

Extreme depth (230 ft) — trimix decompression dive only

Severe cold and darkness at depth

Long offshore boat ride in open Lake Michigan

Entanglement in the self-unloading conveyor structure, A-frame and rigging

Reviews

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