NBM Dive Site Resource
Big Blue Quarry
Mason City, Iowa, United States
A clay quarry in Lester Milligan Park used for shore diving and training, with platforms, sunken boats and freshwater fish.
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.
Bluegill
Lepomis macrochirusCurrent Big Blue dive-site guidance reports abundant bluegill. Divers are most likely to see them around submerged cover, quarry edges, and the shallower water column.
USFWS Mountain PrairieOpen Aquatic Life Profile →
Northern Pike
Esox luciusCurrent Big Blue guidance specifically reports elusive northern pike. Look along deeper edges and vegetated or shaded cover while treating every sighting as condition-dependent.
Jik jikOpen Aquatic Life Profile →
Lake Trout
Salvelinus namaycushMason City tourism guidance states that Big Blue is stocked with lake trout in winter. Encounters are most plausible in cold water and can vary with stocking timing and survival.
Knepp Timothy, U.S. Fish and Wildlife ServiceOpen Aquatic Life Profile →
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.Published reference location
Location map
The marker shows the public coordinates associated with this profile. Confirm current access, moorings, and departure details before the dive.Map data © OpenStreetMap contributors
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
Flooded quarry topography, training features and freshwater ecology.
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
- Confirm current hours, permits, seasonal closures and ice conditions.
- Submerged attractions
- Flooded quarry topography, training features and freshwater ecology.
- Onsite dive services
- Facilities vary; verify toilets, changing areas, fills and rentals before travel.
- Surface facilities
- Facilities vary; verify toilets, changing areas, fills and rentals before travel.
Before you arrive
Access notes
Confirm current park hours, entry rules and dive-flag requirements before entering.
Plan within your training
Conditions and hazards
Cold water, thermoclines, silt, entanglement, steep quarry walls and limited emergency access.
At the site
Facilities and support
Facilities vary; verify toilets, changing areas, fills and rentals before travel.
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.