Flinders Island is app. 62 km from in length from north to south, and 37 km wide from east to west. The island's total land area is 1333 km². Mount Strzelecki at a height of 756 metres, is the island's highest peak.

About a third of Flinders Island is mountainous and rugged with ridges of granite running the length of the island. The coastal areas are dominated by sandy deposits often taking the shape of dunes. Many coastal lagoons are found on the eastern shore, formed by dunes blocking further drainage.

Settlements on Flinders Island include Whitemark, Lady Barron, Blue Rocks, Emita, Killiecrankie, Lackrana, Leeka, Loccota, Lughrata, Memana, Palana, Ranga, Wingaroo, and Wybalenna.