The island's name in Welsh is Ynys Arw, meaning "rugged island".
North Stack can also refer to the headland opposite the island. This is the site of a redundant fog warning station, comprising a number of buildings, including the Trinity House Magazine, built in 1861, where shells for the warning cannon were stored. These buildings now house a bird watching observatory, giving a view of South Stack lighthouse across Gogarth Bay, and the studio of artist Philippa Jacobs. The Precambrian quartzite cliffs of this headland, including North Stack Walls and Wen Zawn, provide some of the most well-known rock climbs in Britain, such as "A Dream of White Horses", "The Cad" and "The Bells! The Bells!"
- "Holyhead Mountain, North Stack to Penrhyn Mawr", ccw.gov.uk. Retrieved 31 December 2010.
- North Stack, holyhead.com. Retrieved 31 December 2010.
- "Artist profile: Philippa Jacobs", bbc.co.uk, Retrieved 31 December 2010.
- Gogarth North Stack (North Stack Wall), ukclimbing.com. Retrieved 31 December 2010.
- Gogarth North Stack (Wen Zawn), ukclimbing.com. Retrieved 31 December 2010.