| Boundary Bay | |
|---|---|
| French: Baie Frontière | |
 Looking east across Boundary Bay from Tsawwassen | |
  Boundary Bay | |
| Location | British Columbia and Washington |
| Coordinates | 49°00′N 122°55′W / 49.000°N 122.917°W |
| Type | Bay |
| Part of | Salish Sea |
| Basin countries | Canada and United States |
| Settlements | Blaine, Delta, Surrey, White Rock |
Boundary Bay is a shallow bay situated on the Pacific coast of North America on the Canada–United States border between the Canadian province of British Columbia and the U.S. state of Washington.