Canada

• Horse Islands (Newfoundland and Labrador), Canada
• Horse Island (Lake Winnipeg), Manitoba

Ireland

• Ardboline Island and Horse Island SPA, 16 km north-west of Sligo town

Northern Ireland

• Horse Island, County Down, a townland
  Townland
  A townland or bally is a small geographical division of land used in Ireland. The townland system is of Gaelic origin—most townlands are believed to pre-date the Norman invasion and most have names derived from the Irish language...
  
   in County Down
  County Down
  -Cities:*Belfast *Newry -Large towns:*Dundonald*Newtownards*Bangor-Medium towns:...
  
  , Northern Ireland
  Northern Ireland
  Northern Ireland is one of the four countries of the United Kingdom. Situated in the north-east of the island of Ireland, it shares a border with the Republic of Ireland to the south and west...
  
  
• Horse Island, County Fermanagh, a townland in County Fermanagh, Northern Ireland

Scotland

• Horse Isle
  Horse Isle
  Horse Isle is an uninhabited island located in the Firth of Clyde, Scotland near the seaside town of Ardrossan. It is a nature reserve, run by the RSPB.-Geography:...
  
   in the Firth of Clyde, North Ayrshire, Scotland
• Horse Island, Shetland in the Shetland Islands, Scotland 59.85°N 01.31°W
• Horse Island, Summer Isles
  Horse Island, Summer Isles
  Horse Island is an uninhabited island in the Summer Isles, in the north west of Scotland.Once inhabited, the island now only supports a herd of wild goats.-Footnotes:...
  
   in the Summer Isles, Scotland 57.98°N 05.34°W
• Eilean nan Each (Horse Island), Small Isles
  Small Isles
  The Small Isles are a small archipelago of islands in the Inner Hebrides, off the west coast of Scotland. They lie south of Skye and north of Mull and Ardnamurchan – the most westerly point of mainland Scotland.The four main islands are Canna, Rùm, Eigg and Muck...
  
  , Scotland

United States

• Horse Island (Connecticut)
• Horse Island (Maryland)
• Horse Island (Michigan)
• Horse Island (Rockville, South Carolina)
• Horse Island (Texas)
• Wild Horse Island
  Wild Horse Island
  Wild Horse Island is the largest island in Flathead Lake, the largest freshwater lake in Montana. For centuries, the Salish-Kootenai used the 2,100 acre island to pasture horses to keep them from being stolen by other tribes...
  
  , Montana
• Horse Island (New York) on Lake Ontario
  Lake Ontario
  Lake Ontario is one of the five Great Lakes of North America. It is bounded on the north and southwest by the Canadian province of Ontario, and on the south by the American state of New York. Ontario, Canada's most populous province, was named for the lake. In the Wyandot language, ontarío means...
  
   just offshore Sacketts Harbor
  Sackets Harbor, New York
  Sackets Harbor is a village in Jefferson County, New York, United States. The population was 1,386 at the 2000 census. The village was named after land developer and owner Augustus Sackett, who founded it in the early 19th century.The Village of Sackets Harbor is within the western part of the...
  
  , Jefferson County
  Jefferson County, New York
  Jefferson County is a county located in the U.S. state of New York. As of the 2010 census, the population was 116,229. It is named after Thomas Jefferson, third President of the United States of America, and president at the time the county was created in 1805...