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Sea Lion Lake
Enhanced dataInteractive depth contours
Sea Lion LakeFlorence County, WI
Contours load with map Access
Interactive depth contours10-foot typical interval · Sonar-derived depth (C-MAP Genesis) · Gaps interpolated · Not for navigation
Source: C-MAP Genesis community sonar (derived)high confidence · QA passed · Select a contour to inspect its mapped depthDepths decoded from C-MAP Genesis Social Map community sonar recordings (used with permission), covering 98% of the lake. Small gaps between recordings are smoothly connected; larger unrecorded areas follow the lake's depth model calibrated to the DNR-documented 82-ft maximum depth. More accurate than a pure model, but still an estimate. Not for navigation.LakeList assistant
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Fishing spots, food, lodging, marinas, and rentals around Sea Lion Lake.
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Fishing
Fishing at Sea Lion Lake
Fishery
Notable species
PanfishLargemouth BassNorthern PikeSmallmouth BassWalleye
Angler reports · Fishbrain
What anglers catch here
Anglers have logged 33 catches on Sea Lion Lake via Fishbrain — 2 in the last 30 days, most recently on Jul 24, 2026.
Most-reported species
- Bluegill
- Largemouth bass
6 of the 33 logged catches didn’t name a species and aren’t listed above.
Counts reflect reporting activity, not fish populations. Waterbody location is provider-level; exact spots and angler details aren’t shown.
Fishery details for this lakeExplore this area on FishbrainWisconsin DNR · 2026–2027 season
Lake-specific fishing regulations
Rule text published by the DNR for this waterbody, cached by WBIC and verified 2026-07-12.
All species
Catch and release fishing for largemouth and smallmouth bass is open year round unless otherwise noted. Motor Trolling is allowed with 1 hook, bait, or lure per angler, and 3 hooks, baits, or lures maximum per boat.
Catfish
Season Dates: Open All Year. No minimum length limit and the daily bag limit is 10.
Cisco and whitefish
Season Dates: Open All Year. No minimum length limit and the daily bag limit is 10.
Lake sturgeon
Season Dates: Closed. No fishing allowed.
Largemouth and smallmouth bass
Season Dates: June 20, 2026 to March 7, 2027. The minimum length limit is 14" and the daily bag limit is 5.
Muskellunge and hybrids
Season Dates: May 2, 2026 to December 31, 2026 on open water. The minimum length limit is 40" and the daily bag limit is 1.
Northern pike
Season Dates: May 2, 2026 to March 7, 2027. No minimum length limit and the daily bag limit is 5.
Paddlefish
Season Dates: Closed. No fishing allowed.
Panfish
Season Dates: Open All Year. No minimum length limit and the daily bag limit is 10, but only 5 can be bluegill.
Rock, yellow, and white bass
Season Dates: Open All Year. No minimum length limit and the daily bag limit is unlimited.
Rough fish
Season Dates: Open All Year. No minimum length limit and the daily bag limit is unlimited.
Shovelnose sturgeon
Season Dates: Closed. No fishing allowed.
Trout and salmon
See Trout regulations layer.
Urban waters gamefish
This waterbody is not considered an urban water, Urban Waters Gamefish regulations do not apply.
Walleye, sauger, and hybrids
Season Dates: May 2, 2026 to March 7, 2027. The minimum length limit is 18" and the daily bag limit is 3.
Regulations can change. The official DNR page controls; verify seasons, boundaries, bag limits, and emergency rules before fishing.
NWS weather
Weather windows
Weather-based planning from the National Weather Service hourly forecast near this lake — not a catch forecast.
Loading latest forecast…
Checking wind, precipitation, and near-term weather windows.
Water temperature
Sea Lion Lake water temperature today
Modeled surface-temperature estimate built from seasonal climate, lake depth, and live National Weather Service air temperatures near this lake.
68°FWarm
Seasonal estimate. Checking current National Weather Service air temperatures…
Comfortable summer pattern. Bass and panfish are active; early and late hours beat the midday heat.
Estimates are modeled, not measured. Actual temperatures vary with depth, wind mixing, and recent weather — verify conditions before swimming, boating, or heading onto ice.
DNR water check
Water quality quick take
From Wisconsin DNR / Citizen Lake Monitoring readings at Sea Lion Lake - Deep Spot.
Last sampled May 2026Volunteer monitoring since 2020
Through 2023, very clear, low-algae water — summer clarity of 22.3 ft puts it among the clearest tenth of monitored Wisconsin lakes.
Based on July–August volunteer averages from 2022–2023; each value shows its own year.31Oligotrophic5-yr summer TSI
Very clear, low-nutrient water — often deep, with limited plant growth.
Water claritySecchi disk depth
22.3 ftJul–Aug 2022 avg (3 readings)
Crystal clearStable since 2004
Clearer than 97% of 593 monitored Wisconsin lakes with current readings.
AlgaeChlorophyll-a
1 µg/LJul–Aug 2023 avg (2 readings)
Very low2004–2023
NutrientsTotal phosphorus — fuels plant & algae growth
10 µg/LLatest single sample · 2021-06-16
Very lowVery low phosphorus means very light plant/algae growth pressure.
All readings by year · station details · methodology
Summer averages (July/August)
July/August means; counts in parentheses show how many samples went into each average.
| Year | Secchi | Chlorophyll-a | Total phosphorus |
|---|---|---|---|
| 2026 | — | — | — |
| 2025 | — | — | — |
| 2024 | 17.0 ft (1) | — | — |
| 2023 | 21.0 ft (1) | 1.0 µg/L (2) | — |
| 2022 | 22.3 ft (3) | 1.0 µg/L (2) | — |
| 2021 | 20.0 ft (2) | 0.5 µg/L (2) | — |
| 2018 | — | — | 14.0 µg/L (1) |
| 2017 | — | — | — |
| 2007 | 15.0 ft (1) | — | — |
| 2004 | 18.0 ft (1) | 1.0 µg/L (1) | 10.0 µg/L (1) |
Latest individual samples: Secchi 27 ft (2026-05-29), chlorophyll-a 1 µg/L (2023-08-19), and total phosphorus 10 µg/L (2021-06-16).
Secchi clarity is how deep a black-and-white disk stays visible from the surface — more feet means clearer water.
Chlorophyll-a is an algae pigment; higher values signal more algae in the water column.
Total phosphorus is a nutrient that feeds algae and aquatic plants. It is not a weed survey — depth, bottom type, water movement, and management change the actual lake experience.
Sea Lion Lake - Deep SpotStation 193039 · TSI based on chlorophyll
Modeled from DNR/CLMN monitoring — not a safety or swim-condition report. Verify current conditions locally. LakeList verified 2026-07-12.Official Wisconsin information
Plan with DNR sources
LakeList links to the authoritative record so you can verify maps, rules, and current notices before leaving.
Historical DNR depth maps1 converted map sheetView DNR depth mapHistorical map · not for navigationFishing regulationsVerify current seasons, limits, and restrictionsOfficial DNR lake pageFacts, advisories, boating, and water qualityWater quality reportsMonitoring stations, clarity, and DNR reportsInvasive speciesVerified, observed, and historical AIS recordsBoating ordinancesLocal slow-no-wake and water-use restrictionsFish consumption advisoriesStatewide and waterbody-specific health guidance
Historical depth maps are not for navigation. Verify regulations and access at the official source before your trip.
Historical Wisconsin DNR maps
Sea Lion Lake depth maps
1 converted map sheet. These historical surveys are not for navigation.
Navigable depth map
Sea Lion Lake · sheet 1
Pan, zoom, and inspect the converted Wisconsin DNR historical map image in the browser. Historical survey — not for navigation.
Source: Wisconsin DNR · WBIC 672300 · image navigation only; spatial alignment pending · Historical lake maps are not for navigation.
Source: Wisconsin Department of Natural Resources. Converted for browser access with source URLs, checksums, and retrieval dates retained. Historical lake maps are not for navigation.
114surface acres
82max depth feet
1public access points
45.8770, -88.3218latitude, longitude
Access
Public access points
Boat launchSea Lion Lake Access45.87836, -88.32269Managed by COUNTYTOWN OF FERNRamp surface: GravelADA-accessible feature: NoVerified 2026-07-12
Nearby
Trip-planning places
No nearby trip-planning places yet
Depth FAQ
How deep is Sea Lion Lake?
Sea Lion Lake is 82 feet deep at its deepest point and averages about 16 feet, according to Wisconsin DNR records.
Is there a free depth map of Sea Lion Lake?
Yes. LakeList publishes a free interactive depth contour map of Sea Lion Lake at a typical 10-foot interval, with an optional 3D underwater view, derived from C-MAP Genesis community sonar (derived) survey data.
Where does the Sea Lion Lake depth map come from?
The interactive depth contours are derived from C-MAP Genesis community sonar (derived). Each contour set passes a visual QA review against the source document before it is published. The depths are derived from community sonar recordings (C-MAP Genesis Social Map, used with permission), with gaps between recordings interpolated; not for navigation.
Trust and freshness
Where this lake data comes from
Wisconsin DNR Lake Mapsname, coordinates, county, source identifiers
LakeList record updated 2026-07-14
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