Field Guides/Cornwall/Diving & Snorkeling
Strong
Best WindowJune through September for warmest visibility; year-round dives possible
Variantsscuba-diving · wreck-diving
RegionCornwall, Ontario

Diving & Snorkeling.

The North Channel between Cornwall and Cornwall Island carries unusually clear freshwater because the Moses-Saunders Power Dam upstream releases well-flushed water from Lake St. Lawrence.

Cornwall Tourism documents the area as a regional freshwater scuba destination, with sheltered conditions on the channel between the Cornwall waterfront and the Akwesasne shore.

Diving & Snorkeling in Cornwall
01 — What to know

The brief.

The river runs cold and clear year-round on the channel below the dam; visibility is typical of dam-controlled tailwater conditions and the channel itself sits sheltered from prevailing west wind by the bulk of Cornwall Island. The dive water is on the international shipping route — the Seaway main channel passes south of Cornwall Island — so divers must observe Seaway navigation rules and stay clear of commercial-shipping lanes.

June through September is the warmest visibility window; year-round dives are possible.

02 — Locations

1. places.

  1. 01

    St. Lawrence River — North Channel

    Between Cornwall and Cornwall Island (Akwesasne side); well-flushed clear freshwater downstream of the Moses-Saunders dam.

03 — Conditions

Today's read.

Air Quality
18
eu-aqi · low
UV Index
1.1
scale 0–11
Humidity
65%
relative
Visibility
27.6 km
clear
Temp
+5.3°
H 14° · L 2°
Sun
05:32 / 20:17
14h 45m daylight
D
Out of season for diving & snorkeling

Temperature (5.3°C) below the typical range and outside the typical season window.