Out Stack is little more than a rocky outcrop, and is uninhabited. It has been described as "the full stop at the end of Britain". Travellers do not encounter any further land masses between Out Stack and the North Pole if heading directly north.
It is said that Lady Jane Franklin, the wife of the Arctic explorer Sir John Franklin landed on the Out Stack, after Dr John Rae's reports of the fate of the Franklin expedition had reached Stromness, Orkney, in 1853/54 where she lived in those days. Although she noted that she wanted to get as close as possible to her missing husband it must be doubted whether or not she landed on Out Stack. The fact that there was no safe landing was one reason—amongst others—why Thomas and David Stevenson decided later in the 1850s to build the lighthouse on Muckle Flugga and not on Out Stack.
The Hermaness National Nature Reserve covers the Muckle Flugga rocks and Out Stack, as well as the seabird cliffs and moorland of Hermaness.