Kirk Deighton SSSI is a Site of Special Scientific Interest (SSSI) in Alton's Field, Kirk Deighton, North Yorkshire, England. This site has been recognised as having one of the largest known breeding populations of great crested newts in the United Kingdom. It is a Special Area of Conservation, and is listed for protection under a number of directives. This ordinary-looking grassland field, with a couple of ponds in it, is ideal habitat for the newts, which use the grassland for foraging, the ponds for breeding, and surrounding walls, hedges and woodpiles for hibernation. The site is not accessible to the public, and it is not permissible to survey the ponds without a licence.