How deep is Portsmouth Mine Pit Lake?

Portsmouth Mine Pit Lake has a depth range of 3–137.2 metres (10–450 feet). Check the dive site page for current conditions and any depth-specific guidance before planning your dive.

Can beginners dive Portsmouth Mine Pit Lake?

Portsmouth Mine Pit Lake is rated as intermediate difficulty, which may not suit new divers. A Open Water for shallow shelves; Advanced/technical training for wall dives below 60 ft certification or equivalent is suggested. Consider your experience level, conditions, and local guidance before planning.

When is the best time to dive Portsmouth Mine Pit Lake?

The best time to dive Portsmouth Mine Pit Lake is typically May through October. Conditions vary, so check the latest reports and forecasts on the dive site page before your trip.

What will I see at Portsmouth Mine Pit Lake?

Divers at Portsmouth Mine Pit Lake in United States commonly report sightings of Rainbow trout, Smallmouth bass, Northern pike, and Crayfish. Marine life varies by season and conditions—check the site page for recent diver observations and photos.

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IntermediateShore entry

Portsmouth Mine Pit Lake

Minnesota, United States

Open Water suggested3–137 m depthShore entry

Portsmouth Mine Pit Lake at a glance

Portsmouth Mine Pit Lake is a intermediate shore dive site in Minnesota, United States with depths of 3–137.2 m (10–450 ft). Typically most favorable Jan · from 3 years of archive data. Divers commonly see Rainbow trout, Smallmouth bass, and Northern pike. Check the latest conditions and entry details before you go.

Wind model · graded 9h ago

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Tap a factor for its source and model point

Site hazards: Extreme depth beyond recreational limits, steep walls, cold water below thermocline, submerged trees and mine debris

Read the full hazards ↓

Dive windows this week

Best: Fri

Mon6:00–21:00

Tue6:00–21:00

Wed6:00–18:00

Thu6:00–21:00

Fri6:00–21:00

Sat6:00–21:00

Sun6:00–20:00

Favorable windowModerate window— no window

First light 5:15 · Sunrise 5:51 · Sunset 20:53

Source: Open-Meteo wind · graded 9h ago

Forecast only — always assess conditions on site.

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.

What Divers Say

Known for: Rainbow trout, Crayfish

Best time: May through October

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.

Jan96% 9 kn
Feb89% 10 kn
Mar85% 11 kn
Apr73% 12 kn
May83% 11 kn
Jun82% 11 kn
Jul90% 9 kn
Aug87% 10 kn
Sep94% 10 kn
Oct77% 11 kn
Nov88% 10 kn
Dec86% 10 kn

January hastypically 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

Rainbow troutCommonly seen
Smallmouth bassOccasionally seen
Northern pikeOccasionally seen
CrayfishCommonly seen

Fills & rentals nearby

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

Site details

A flooded iron-ore pit on the edge of Crosby in the Cuyuna Range, and at roughly 400-450 ft the deepest lake entirely within Minnesota. Its rock-filtered water gives up to 50 ft of visibility, and divers work the sheer walls, shelves and old mine features; most recreational dives stay in the 30-100 ft range while technical divers go far deeper. The Minnesota School of Diving in Brainerd leads group dives here several days a week from May through October.

shorewall

Extreme depth beyond recreational limits, steep walls, cold water below thermocline, submerged trees and mine debris

Reviews

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