Originally called Southampton Port, it was renamed as a result of its heavy fortification in the early decades of the Seventeenth century.
An unincorporated settlement, Tucker's Town, was established on the peninsula of the Main Island at the south-west of the harbour.
There are many islands and beach areas in the harbour, and numerous subterranean waterways link its waters with that of Harrington Sound in the southwest, notably Crystal Cave.
[4] Initial fortification by the Virginia Company's (Bermuda was originally settled as an extension of Virginia) first deliberate settlers in 1612, was around the inlets to St. George's Harbour, but by the end of that year work had commenced on Castle Harbour's defences, starting at Castle Island (previously called Gurnett's Head, and King's Island.
Although neither struck, the Spanish vessel abandoned the attack (its crew did not realise that the gunners in the fort had only enough ammunition for one more shot).
This fort was used as late as the Second World War by Bermuda's military garrison, with soldiers living in tents within its walls, watching over the channels with machine guns.
Castle Harbour is the only breeding ground in the world of the famous rare seabird, the Bermuda petrel or cahow.
The north of the harbour was altered considerably during the Second World War, when the US Army built a large airbase, Kindley Field, which is today the Bermuda International Airport.