NBM Dive Site Resource
Gilboa Quarry
Ottawa, Ohio, United States
A spring-fed former limestone quarry and year-round freshwater dive destination near Ottawa, Ohio, with clear water, shallow training areas, technical depths, abundant fish, and an extensive collection of submerged attractions. Certified divers, students under professional supervision, freedivers, snorkelers, swimmers, and paddlers are welcome under current site rules.
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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.
American Paddlefish
Polyodon spathulaThe quarry advertises giant resident paddlefish, including animals over four feet long; sightings vary with depth and conditions.
USFWSOpen Aquatic Life Profile →
Common Carp
Cyprinus carpioThe operator identifies koi among the quarry fish divers may encounter; koi are the ornamental form of common carp.
George ChernilevskyOpen Aquatic Life Profile →
Lake Sturgeon
Acipenser fulvescensGilboa describes an occasional sturgeon encounter and separately identifies a lone resident sturgeon, so sightings should not be expected on every dive.
Ryan Hagerty/USFWSOpen 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
Official conditions
Current temperatures
Automatically checked twice daily. The most recent successful reading remains visible if the source is temporarily unavailable.Source updated Oct 29, 2026 · Last checked Nov 10, 2026, 5:05 PMGilboa Quarry ↗
Why divers know this place
Highlights
Spring-fed clarity; giant paddlefish, trout, koi, bass, bluegill, catfish, and occasional sturgeon; Nemo's Garden freshwater underwater biosphere; a 36-foot Grumman Gulfstream I airplane; a 35-foot Sikorsky S-56 Mojave helicopter; submerged boats, school buses, trees, limestone walls, swim-throughs, six scuba docks, and ten training platforms.
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.
- Former use
- Dolomite limestone quarry dating to the 1890s; operated by Ottawa Stone Company from the late 1950s through the early 1980s and developed as a dive site beginning in 1990
- Current operating status
- Year-round private dive and recreation center; hours vary by season and ice diving depends on certification, planning, and weather
- Entry points
- Six scuba docks plus shoreline, swim-area, and paddle launch access
- Training platforms
- Ten dedicated underwater training platforms at varied depths on the shallow side
- Submerged attractions
- 36-foot Grumman Gulfstream I airplane, 35-foot Sikorsky S-56 Mojave helicopter, school buses, boats, flooded trees, limestone walls, swim-throughs, and Nemo's Garden freshwater underwater biosphere
- Onsite dive services
- Air, Nitrox 32, custom oxygen blends from 22%-100%, 100% oxygen, rebreather fills, gear rentals, dive shop essentials, rinse tank, and classroom reservations; trimix is not currently available on site
- Surface facilities
- Parking, picnic areas, swim beach, bathhouse with hot showers and changing rooms, tent and RV camping, lodging options, snacks and drinks, kayak and paddleboard rentals
Before you arrive
Access notes
A current waiver and appropriate visitor pass are required. Unsupervised scuba divers must hold certification from a recognized agency; students and non-certified participants may dive only under direct professional supervision. The buddy system is required except for properly certified self-reliant divers who register at the front desk. Confirm current hours, rates, rental availability, and operating rules before travel.
Plan within your training
Conditions and hazards
Cold water and strong thermoclines, depths to 140 ft, reduced visibility during busy periods, submerged structures and possible overhead or entanglement hazards. Use exposure protection appropriate for the season and depth, remain within training limits, follow the buddy rule and all current quarry safety requirements, and attempt ice diving only with proper certification and planning.
At the site
Facilities and support
On-site dive shop and fill station with air, banked Nitrox 32, custom oxygen blends from 22%-100%, 100% oxygen, and rebreather fills (no on-site trimix); recreational dive-gear rentals; rinse tank; ample parking with limited quarry-side spaces; picnic areas; classroom reservations; snacks and drinks; 24/7 bathhouse with hot showers, changing rooms, sinks, and flush toilets; tent camping, reservable RV sites with water and up to 50-amp electric service, and additional lodging options.
Additional contributor media
Video gallery
Additional Dive Site videos appear here after the three featured video positions are filled.
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.