How deep is Portsmouth Mine Pit Lake?

Portsmouth Mine Pit Lake ranges from 3 to 137.2 metres deep (10–450 feet) — a deep dive at its limit. It is a freshwater site rated as intermediate difficulty. Depths vary across the site, so plan your profile to your training and verify conditions locally.

Is Portsmouth Mine Pit Lake a shore dive or a boat dive?

Portsmouth Mine Pit Lake is a shore dive — you can enter from land. The entry is recorded as an easy walk-in. The entry area is recorded as sheltered from surge. Basic facilities are recorded at or near the site, and cell service is recorded as good. Entry details and parking notes, where known, are listed in the access section of this page.

Can beginners dive Portsmouth Mine Pit Lake?

Portsmouth Mine Pit Lake is rated as intermediate difficulty, which may not suit new divers. Listed depths run from 3 to 137.2 metres (10–450 feet). Access is from shore, with the entry recorded as an easy walk-in. 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 Northern pike, Rainbow trout, Crayfish, and Smallmouth bass. Rainbow trout and Crayfish are recorded as common sightings, while Northern pike and Smallmouth bass are reported only occasionally. 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 StatesDirections

Open Water suggested3–137 m depthShore entry

Portsmouth Mine Pit Lake at a glance

Portsmouth Mine Pit Lake is an 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 Northern pike, Rainbow trout, and Crayfish. Check the latest conditions and entry details before you go.

Wind model · graded 14h 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: Sun

Fri14:00–15:00

Sat7:00–8:00

Sun7:00–20:00

Mon—

Tue11:00–20:00

Wed7:00–20:00

Thu7:00–18:00

Favorable windowModerate window— no window

First light 6:18 · Sunrise 6:49 · Sunset 19:35

Source: Open-Meteo wind · graded 14h 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.

Dived here today — did the forecast match?

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

Fills & rentals nearby

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

Data updated June 2026

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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