Conception Bay covers an area of 1295 square kilometers and contains several islands, the three major ones being Bell Island, Little Bell Island and Kelly's Island. The Bay is fed into by rivers from both the east and west side of the bay, which are then fed into the Atlantic Ocean.
The name Conception Bay comes from the Portuguese Baia de Conceicao or Baia de Comceica and was presumably given in honour of the Feast of the Conception, December 8. The name first appears on the Oliveriana map of 1505 – 1508.
From the late 1890s to the 1960s, Bell Island was home to an iron ore mine in Wabana operated most recently by the Dominion Steel and Coal Corporation (DOSCO); the ore was shipped to DOSCO's steel mill in Sydney, Nova Scotia. During World War II, DOSCO cargo ships sitting at anchor, along with the loading pier at Wabana, were the target of German U-boats on at least two occasions. During one particular attack on ore carriers sitting at anchor, a torpedo missed its target and struck the pier, making Bell Island one of the few places in North America to suffer a direct enemy attack (see Attacks on North America during World War II). The wrecks of the 4 cargo ships sunk during these two attacks are visible at low tide; a memorial on shore is dedicated to the 69 merchant sailors who lost their lives.
The provincial government operates a passenger-vehicle ferry service from Bell Island to Portugal Cove (on the bay's southeastern shore), operating through what locals know as the "Bell Island Tickle."
Humpback whales have been known to enter the bay while migrating. Private vessels and tourist charters frequent the bay's waters during the summer months.
Property development in the St. John's exurb of Conception Bay South in recent decades has led to increasing recreational use of the bay.