| Castel Bay | |
| Location: | M'Clure Strait |
| Coords: | 74.2006°N -119.5864°W |
| Oceans: | Arctic Ocean |
| Countries: | Canada |
| Pushpin Map: | Canada Northwest Territories |
| Cities: | Uninhabited |
Castel Bay is a Canadian Arctic waterway in the Northwest Territories. It is a southern arm of M'Clure Strait on northeast Banks Island. The mouth of the larger Mercy Bay is less than to the east.These bays are a part of Aulavik National Park.
It is named by Vilhjalmur Stefansson in honour of Arctic explorer Aarnout Castel.[1] [2]