[1] The Old Man of Hoy, a sea stack formed from Old Red Sandstone, can be found in the northwest on the Rackwick coast.

The highest point on the island (and the whole archipelago) is in the north at Ward Hill, which stands at 481 metres (1,578 ft).

[16][Note 2] The two most northerly Martello Towers in the UK stand here, built in 1814 to defend merchant shipping in the natural harbour of Longhope against privateers commissioned by United States President James Madison, who declared war in 1812.

[citation needed] The main naval base for the British fleet in both the First and Second World Wars, Scapa Flow, was at Lyness in the southeast of the island.

During the early years of the Second World War, up to 12,000 personnel were based in and around Lyness to support the defences of the naval anchorage at Scapa Flow and the ships that used it.

Offices, workshops, stores and recreational buildings were erected, including a cinema, a theatre and several churches.

An earlier headquarters building was replaced in 1943 by an imposing concrete HQ and communications centre, also sited high on Wee Fea, which now serves as a hotel.

It was stationed there as it meant that the lifeboat could be dragged over wooden skids into the sea in either North Bay, giving access to Scapa Flow, or in Aith Hope, an offshoot of the notorious Pentland Firth to the south.

This class was designed to stay permanently afloat, and the decision was taken to move her to purpose-built moorings at Longhope pier.

[23][24] The northern part of the island is an RSPB reserve due to its importance for birdlife, particularly great skuas and red-throated divers.

[25] Anastrepta orcadensis, a liverwort also known as Orkney Notchwort, was first discovered on Ward Hill by William Jackson Hooker in 1808.

[26][27] The northern and western parts of Hoy, along with much of the adjoining sea area, is designated as a Special Protection Area[28] due to its importance for nine breeding bird species: arctic skua, fulmar, great black-backed gull, great skua, guillemot, Black-legged kittiwake, peregrine falcon, puffin and red-throated diver.

There is the remote possibility of locally extant Orkney charr (Salvelinus inframundus) documented in 1908 at Heldale Water.

[32][33] In Poul Anderson's story "The Bitter Bread" the protagonist lives in secluded retirement on Hoy.

There is a description of the island: "Steep red and yellow cliffs, sea green in sunlight or gray under clouds until it breaks in whiteness and thunder, gulls riding a cold loud wind, inland the heather and a few gnarly trees across hills where sheep graze, a hamlet of rough and gentle Orkney folk an hour's walk away, my cat, my books, my rememberings.