Climate:
Saint Helena: tropical marine; mild, tempered by trade winds
Ascension Island: tropical marine; mild, semi-arid
Tristan da Cunha: temperate marine; mild, tempered by trade winds (tends to be cooler than Saint Helena)
Terrain:
the islands of this group result from volcanic activity associated with the Atlantic Mid-Ocean Ridge
Saint Helena: rugged, volcanic; small scattered plateaus and plains
Ascension: surface covered by lava flows and cinder cones of 44 dormant volcanoes; ground rises to the east
Tristan da Cunha: sheer cliffs line the coastline of the nearly circular island; the flanks of the central volcanic peak are deeply dissected; narrow coastal plain lies between The Peak and the coastal cliffs
Elevation extremes: