NBM Dive Site Resource
Portsmouth Mine Pit — Cuyuna Country
Crosby, Minnesota, United States
A very deep, clear flooded mine pit in Cuyuna Country State Recreation Area specifically identified for scuba diving by Minnesota DNR.
Save this dive site to your free member profile.
Quarry Picture Placeholder
Aquatic life at this dive site
What divers may encounter
Three reviewed connections are featured here. Sightings vary by season, conditions, and chance, so they are never guaranteed.
Aquatic life research in progress
NBM is reviewing a likely local species for this position.
Aquatic life research in progress
NBM is reviewing a likely local species for this position.
Aquatic life research in progress
NBM is reviewing a likely local species for this position.
Site media
Photographs
Three views rotate from the published gallery on each visit.
Contributor media
Dive videos
Three featured video positions are reserved on every profile.Recent field observations
Diver-reported temperatures
Automatically checked observations from dives during the past 14 days. Three reports are visible at a time; scroll for more.A report that passes the automatic checks will appear here with the dive date, diver’s display name, and temperatures at each depth.
Reports are automatically checked for plausible dates, depths, and temperatures. They are observations, not forecasts; confirm conditions before diving.
Why divers know this place
Highlights
Clear mine-pit water, dramatic walls and long-established Cuyuna dive access.
Quarry-only module
Quarry layout and services
This section appears only for quarries and mines, with the practical details divers need for entries, training areas, submerged features, surface support, and current operations.
- Current operating status
- Cold-water diving during practical open-water conditions; confirm ice and road access.
- Submerged attractions
- Clear mine-pit water, dramatic walls and long-established Cuyuna dive access.
- Onsite dive services
- State recreation-area facilities vary; bring full dive support unless a local operator confirms services.
- Surface facilities
- State recreation-area facilities vary; bring full dive support unless a local operator confirms services.
Before you arrive
Access notes
Use a current local map and briefing. The pit is much deeper than recreational limits and must not be treated as uniformly beginner-friendly.
Plan within your training
Conditions and hazards
Extreme depth, cold water, thermoclines, silting, entanglement and remote-access considerations.
At the site
Facilities and support
State recreation-area facilities vary; bring full dive support unless a local operator confirms services.
Independent resource notice
This record is a starting point for independent verification. Access, closures, moorings, weather, currents, depth, visibility, operator availability, and site conditions can change without notice. Confirm current information with the responsible operator, property owner, managing authority, or another qualified local source before planning or attempting a dive.