Ísafjarðardjúp is a large fjord in the Westfjords region of Iceland. Its name translates as Ice fjord deep.
Ísafjörður, capital of the Westfjords region, is situated close to the mouth of Ísafjarðardjúp.
The north-eastern coast is fairly straight with the only inlet being Kaldalón, but the southern side has fjords extending well into the land: Skutulsfjörður, Álftafjörður, Seyðisfjörður, Hestsfjörður, Skötufjörður, Mjóifjörður and Ísafjörður. These names translate respectively as: Shettel's fjord (shettel being a crooked object shot to capture fish), Swan fjord (the birds are frequently found here), Seed's fjord, Horse's fjord, Flounder-fjord, Meager fjord (this fjord is small, and spanned by a bridge), and Ice fjord.
Three islands lie in Ísafjarðardjúp: Borgarey, Æðey and Vigur with Borgarey the smallest with no inhabitants and Æðey the largest. On both Æðey and Vigur there is one farmstead.