Tags: Site Of Special Scientific Interest.
Castle Down is a windswept plateau of maritime heath in the northern part of the island of Tresco Isles of Scilly. The area has a number of designations including Castle Down (Tresco) Site of Special Scientific Interest (SSSI); is part of the Isles of Scilly Area of Outstanding Natural Beauty; part of the Isles of Scilly Heritage Coast; and part of Plantlife’s Isles of Scilly Important Plant Area.