A Site of Special Scientific Interest (SSSI) (Area of Special Scientific Interest or ASSI in Northern Ireland) is a conservation designation denoting a protected area in the United Kingdom. SSSIs are the basic building block of site-based nature conservation legislation and most other legal nature/geological conservation designations in Great Britain are based upon them, including national nature reserves, Ramsar sites, Special Protection Areas, and Special Areas of Conservation. The acronym "SSSI" is often pronounced "triple-S I".