The Saltees are a haven for sea birds, nurturing an impressive array of birds, from Gannets and Gulls to Puffins and Manx Shearwaters. They also lie on an important migratory route and a popular stopping-off place for spring and autumn migrants. The Great Saltee also has a breeding population of Grey Seals, one of the very few in eastern Ireland. Up to 120 animals are present in autumn and up to 20 pups are produced annually.

The Saltees are among the ancient islands of Europe, based on Pre-Cambrian bedrock i.e. between 600 and 2000 million years old. Primitive Stone Age man first settled there before history was recorded and carved out an existence. As long ago as 3,500 to 2,000 B.C. there were people on the islands. There is a recently-identified promontory fort, the remains of an ancient grave, an Ogham stone (now in a local museum) and traces of what appear to be ring forts.