Ungava Bay is a large bay in northeastern Canada separating Nunavik (far northern Québec) from Baffin Island. The bay is shaped like a curved square with a side length of about 180 kilometres and has an area of approximately 33,000 km² (12,720 mi²). It is generally fairly shallow, though at its border with the Atlantic Ocean depths of 300 metres (980 feet) are reached.

There are a number of islands within Ungava Bay. The largest, Akpatok Island, and others north of 60 ° N are part of the territory of Nunavut, whilst smaller islands south of 60 ° N belong to Québec.

Although it is quite close to the open Atlantic (separated only by Hudson Strait), Ungava Bay is generally considered part of the Arctic because the land surrounding it has an exceedingly cold climate. Due to the influence of the Labrador Current, summers are too cold for tree growth and all the land surrounding the bay is treeless tundra. Typically, temperatures in summer at Fort Chimo about twenty kilometres up the Koksoak River are about 7 ° C (44 &deg' F), whilst winter temperatures are about -20 ° C (-4 ° F). Precipitation averages around 400-450 millimetres per year, most of it falling in the summer.

Ungava Bay is surrounded by numerous Inuit villages, the largest of which is Kuujjuaq at the mouth of the Koksoak River. Iron ore has been mined in the past, but despite the high grade of the ores the impossibility of cheap transportation meant that mining was discontinued early in the twentieth century. Traditional Inuit hunting activites still dominate the region's life, along with expensive adventure tourism.

The southwestern corner of Ungava Bay has either the highest or second-highest tidal ranges in the world. Some sources estimate the spring tide range at the mouth of the Leaf River (Rivière aux Feuilles ) as being as high as seventeen metres or fifty-six feet. Attempts have been made to develop tidal power in the bay, but this is made difficult by the harsh climate and the fact that the bay is ice-free for only a small part of the year.