Ontario Lake Depths
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Semiwite Lake

Algoma District, Ontario · MNRF bathymetric survey
33.5m Mapped depth
110 ft
310 ha 11 contours
Paddling Index62MixedMedium confidencewooded shoreline
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Depth scale

The lake

Survey readout

Semiwite Lake is mapped to a depth of 33.5 m (110 ft) on the Ontario MNRF survey and covers about 310 ha (766 acres) in Algoma District, Ontario. Depths come from the Ontario MNRF survey of 1967.

Measured from the Ontario MNRF bathymetry survey.

Deepest mapped contour
33.5 m (110 ft)
Survey year
1967
Surface area
310 ha (766 acres)
Shoreline
11.8 km (7.4 mi) · irregular
Fishing access
No MNRF launch listed · check with Mississagi Provincial Park
In
Mississagi Provincial Park · Ontario Parks
Additional depth details11 contours
Contour depths
0–33.5 m (110 ft)
Deep-spot markers
33.5 m (110 ft)
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Chart data

Provenance

Sources: Ontario MNRF / LIO Bathymetry, Ontario FRI Leaf-On Imagery, Ontario FRI LiDAR DTM, OpenStreetMap (ODbL), Contains information licensed under the Open Government Licence – Ontario.

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Map details & sources5 sources

All layers registered to one bounding box; positions in WGS 84.

Survey-derived depth contours drape over Ontario LiDAR (FRI DTM) elevation, with a Ontario FRI aerial basemap and OpenStreetMap shoreline. Colour shows surveyed depth; dark lines are the survey's own isobaths.

Coordinates
46.57551, -82.67732
MNRF lake ID
17-3712-51594
Vertical exaggeration
1.4×
Basemap
Ontario FRI
Model size
1.5 MB

Check the source: this lake’s record (17-3712-51594) in the Ontario MNRF bathymetry index, and the contour line layer the map is drawn from (Land Information Ontario open data, Open Government Licence – Ontario). Survey year: 1967. This model was built 2026-09-08. Depths between contours are interpolated, not measured.

Paddling

Paddling Index methodology v1.0 · calculated 2026-09-16
62 / 100MixedData confidence: Medium

Semiwite Lake has a heavily wooded and largely undeveloped setting, notable open-water exposure, some nearby classified roads.

Why this score?5 components

Included in the index

ComponentRatingPoints of weightMeasurement
Natural settingExcellent40.1 of 4394% natural land cover within 150 m of shore (87% forest, 6% wetland; 2% developed)
Geometric wind exposureMixed10.5 of 36mean fetch 2,224 m · 1% of sampled water within 500 m of shelter · long fetch in some directions
Motor & speed rulesNot modelled—Canada publishes vessel motor and speed restrictions as federal legal schedules, not map data, so they are not part of the Ontario index. Check local signage and Transport Canada rules before going out.
Public accessNot listed—No publicly listed MNRF fishing access point within 100 m of this shoreline. Municipal, private and informal launches are not all in this source, so this is not evidence that access is poor — the component is excluded and the remaining weights are renormalized.
Road isolationGood11.0 of 21some nearby classified roads · 33 Ontario Road Network segments within 1.2 km (traffic estimated from road class, not measured)

Additional paddling considerations

These describe the lake but are not part of the v1 Paddling Index and do not change the number above.

Wake sensitivity
Low — wide enough that wakes disperse over most of the lake
Observed motorized activity
Unknown — No lake-level measurement of boat traffic is available. Legal permission to operate motors is not evidence of use.
Wildlife habitat potential
High — 87% forest and 6% wetland cover within 150 m of shore
Mapped wildlife habitat
None mapped — Ontario MNRF has not mapped moose, deer or waterfowl habitat within 1 km of this lake. The province maps these areas where it has surveyed, so this is not evidence that wildlife is absent. · Ontario MNRF Wildlife Values Area. Contains information licensed under the Open Government Licence – Ontario.
How this index is calculated. The Paddling Index is a relative composite derived from lake geometry and public land-cover, access and road-network data. It is not a user review, a safety rating, or a prediction of an individual outing. Differences of a few points should not be treated as meaningful — an 84 and an 82 are broadly comparable. Components and weights for Ontario lakes: natural setting 35%, geometric wind exposure 29%, public access 18%, road isolation 18%. Motor and speed restrictions are not modelled for Ontario, and road traffic is estimated from road class, not measured. Where a component has no data the remaining weights are renormalized and the confidence rating is lowered; below Medium confidence no number is shown. Ontario scores are relative to other Ontario lakes and are not directly comparable with Paddling Index scores on our sister sites, which use different data sources and include a watercraft-rules component. Sources: Ontario MNRF bathymetry outline (0 m contour or survey index polygon), Ontario Land Cover v1.0, Ontario MNRF (Open Government Licence – Ontario) (2020) and Ontario Road Network (Open Government Licence – Ontario); traffic estimated by road class, not measured (2026-09). Conditions change quickly — check current weather and local conditions before going out.

Angler catch reports

Fish ON-Line · 2018–2021

4 angler trips logged here between June 2018 and August 2021 — too few to show a pattern, so each species is listed with how many trips named it.

Pictures are sized relative to each other. Illustrations are AI-generated representative adults in everyday colours, not photographs (provenance).

Lake Trout4 of 4 trips · 8 caught
Rock Bass1 trip · one angler’s report · 1 caught
Trips are logged voluntarily by anglers in Ontario’s Fish ON-Line app. This is what people report catching, not a Ministry survey, and a species nobody has logged may still be here. Contains information licensed under the Open Government Licence – Ontario. Source: Ontario Ministry of Natural Resources, Fish ON-Line. A logged catch does not mean it is legal to catch or keep: check the Ontario Fishing Regulations Summary for this lake’s zone and exceptions.
Quick answers

Semiwite Lake — common questions

How deep is Semiwite Lake?

The deepest contour on the Ontario MNRF bathymetric survey of Semiwite Lake is 33.5 m (110 ft). That is the deepest depth the historical survey map records, which may differ from the deepest point of the lake itself.

How big is Semiwite Lake?

Semiwite Lake covers about 310 ha (766 acres) in Algoma District, Ontario.

Is there public access to Semiwite Lake?

No fishing access point for Semiwite Lake appears in the Ontario MNRF fishing access point list (within 100 m of the shoreline), but Semiwite Lake lies inside Mississagi Provincial Park (Ontario Parks), which runs its own facilities and is not covered by that data. Check with the park for launch details.