Dow's Lake, reservoir on the Rideau Canal in Ottawa, Ontario, Canada

Dow's Lake is a man-made widening of the Rideau Canal in central Ottawa, created by an earthen dam whose line now carries the north part of Queen Elizabeth Driveway. A pavilion with three restaurants and boat rentals stands at the northern end, and a white cabin cruiser and a wooden boat with a varnished cabin are moored along the near shore. A large building with a wide sloping white roof and a tall dark tower rises behind the water.

The lake is named after Abram Dow, an American-born settler who owned land here in 1816, when the area was called Dow's Great Swamp. It was created by an earthen dam along the north shore, now topped by Queen Elizabeth Driveway, to flood the Rideau Canal. The canal was routed between the lake and Entrance Bay after land speculation by Lieutenant John LeBreton was rejected by Lord Dalhousie and Colonel John By.

The lake is named after Abram Dow, an American-born settler who owned land here in 1816, when the area was called Dow's Great Swamp. The name stuck after the Rideau Canal dam flooded the swamp. Each May, Commissioners Park on the northeast shore hosts part of the Canadian Tulip Festival, with about 300,000 tulips of more than 50 varieties; the Dutch royal family sends 10,000 tulips yearly.

The area offers easy access with walking and biking paths around the water suited to different abilities. Summer visitors can rent canoes, kayaks, or paddle boats, while winter allows for skating on the frozen surface.

The lake is named after Abram Dow, an American-born settler who owned land here in 1816, when the area was still called Dow's Great Swamp. A rail tunnel completed on 5 August 1967 passes beneath the canal at the lake's southwest corner; since 2001 it has carried only O-Train diesel trainsets.