Thousand Islands National Park

There are two sand beaches at Thousand Islands National Park. One is on Central Grenadier Island and the other is on Thwartway Island. However, there are plenty of great swimming rocks and docks throughout the park.

For more information on natural hazards, weather conditions, and planning a safe activity, please see our Visitor Safety page.

Safe swimming

  • Swim in areas that are away from high boat traffic. Parts of the river are busy with cruise ships, power boats, cargo ships and other vessels.  Boat operators in these areas may not expect swimmers or be able to see them.
  • There are no lifeguards at any of the park beaches. Visitors are responsible for their own safety.  Swim with a buddy and supervise children when near the water.
  • River currents can be strong, even for an accomplished swimmer. Always be aware of the current and avoid high risk areas.
  • The park beaches are not tested for E. coli or other bacteria.
  • Some parts of the river are home to the invasive zebra mussel. Zebra mussel shells can be sharp and swimming footwear (water shoes or sandals) are recommended to protect your feet from cuts.
  • Water temperatures suitable for swimming are generally reached by June and continue through August. Swimming during the spring and fall in cold water can increase the risk of hypothermia. Be aware of hypothermia and how to treat it.

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