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IntermediateBoat entry

Glenlyon

Michigan, United States
Open Water suggestedVery cold water (surface rarely above 13 C / 55 F, 1-3 C below 50 ft) increases DCS risk; extreme remoteness5–18 m (15–60 ft) depthBoat entry

Boat dive — see Entry & access.

Glenlyon at a glance

Glenlyon is an intermediate boat dive site in Michigan, United States with depths of 4.6–18.3 m (15–60 ft). Typically most favorable Jul · from 3 years of archive data. Divers commonly see Lake trout, Burbot, and Slimy sculpin. Check the latest conditions and entry details before you go.

Favorable window now· until 19:00 · sunset 18:46

Wind forecast for this hour · 9:00 · run 19 h ago
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Tap a factor for its source and model point

Site hazards: Very cold water (surface rarely above 13 C / 55 F, 1-3 C below 50 ft) increases DCS risk; extreme remoteness

Read the full hazards ↓

Dive windows this week

Lightest wind: Sat
Mon9:00–19:00 favorable

6 kn wind (6 kn wind)

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

11 kn wind (11 kn wind)

Wed17:00–19:00 moderate

12 kn wind (12 kn wind)

Thu9:00–19:00 favorable

10 kn wind (10 kn wind)

Fri9:00–19:00 favorable

6 kn wind (6 kn wind)

Sat9:00–19:00 favorable

4 kn wind (4 kn wind)

SunNot in the forecast yet

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 7:59 · Sunrise 8:31 · Sunset 18:46 · some windows run past sunset

Source: Open-Meteo wind · updated 25 Oct, 13:22 GMT-4

Forecast only — always assess conditions on site.

Compare this weekend’s windows near Glenlyon

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: July through early September, when Lake Superior is calmest and surface temperatures peak.

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, 40% of days have historically been favorable, wind has typically been 15 knots
  2. February, 40% of days have historically been favorable, wind has typically been 15 knots
  3. March, 49% of days have historically been favorable, wind has typically been 14 knots
  4. April, 44% of days have historically been favorable, wind has typically been 15 knots
  5. May, 59% of days have historically been favorable, wind has typically been 13 knots
  6. June, 72% of days have historically been favorable, wind has typically been 12 knots
  7. July, 86% of days have historically been favorable, wind has typically been 10 knots, historically most favorable
  8. August, 76% of days have historically been favorable, wind has typically been 12 knots
  9. September, 70% of days have historically been favorable, wind has typically been 12 knots
  10. October, 43% of days have historically been favorable, wind has typically been 15 knots
  11. November, 32% of days have historically been favorable, wind has typically been 16 knots
  12. December, 45% of days have historically been favorable, wind has typically been 16 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 Glenlyon was a 328-ft steel package/bulk freighter built in 1893 that ran aground on a shoal off Menagerie Island while seeking shelter in Isle Royale's Siskiwit Bay on November 1, 1924, carrying 143,000 bushels of wheat. The wreck is broken and scattered across the reef in 15-60 ft of water, with the bow on the bay side of the shoal and the stern on the lake side, but the pieces lie close to their original positions and large sections — including the engine room with triple-expansion engine, drive shaft, propeller, and boilers — remain intact. Listed on the National Register of Historic Places, it is one of the ten major wrecks protected within Isle Royale National Park.

boatwreck

Very cold water (surface rarely above 13 C / 55 F, 1-3 C below 50 ft) increases DCS risk; extreme remoteness — nearest recompression chambers are in Minneapolis and Milwaukee; rapidly changeable Lake Superior weather and waves over the shallow shoal; entanglement in scattered steel wreckage and cable; low light on overcast days.

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