[2] The coast line 200 m (660 ft) from the Smooth Island waterline has been classified Zone 23 (Environmental management) under the Tasman Interim Planning Scheme 2015.

[3][4] Smooth island is private property to the coastal high-water mark; unauthorised public access, including mooring of vessels, is prohibited.

Smooth Island consists of diabase or dolerite rock, a subvolcanic intrusion that probably occurred from 56 to 33.9 million years ago during the Eocene epoch of the Cenozoic era.

[15] A geological survey identified consolidated, brownish, fine-grained quartz sandstone occurring on the island's north-east coastline at approximately 2 m (6.6 ft) above sea level, covered by sand.

[16][17] The western aspect of the island contains dolerite (tholeiitic) with locally developed granophyre from the Jurassic period.

[18] Because the island predominantly has a sloping hard rock shore, there is little vulnerability to flooding or erosion due to a rise in sea level.

[19] A coastal acid sulfate soil analysis produced a result of "extremely low" along the north and north-east side of the island.

[20] Studies have found dense populations of South Australian cobbler (Gymnapistes marmoratus) within this region because this fish prefers patchy beds of eelgrass.

[25] The fish species flathead, trumpeter, perch, cod and Australian salmon can be found in the waters immediately surrounding the island.

[27][28] The Spotted handfish and the Live-bearing Seastar (Parvulastra vivipara) are threatened marine species that may be present in the waters surrounding Smooth Island.

[32] The island's natural vegetation has been largely displaced by exotic grass, thistle, bracken, scattered eucalypts and African boxthorn bushes.

[39] During the early 21st century, Smooth Island was occasionally listed as "Lot 1 Norfolk Bay, Dunalley TAS 7177" on some real-estate classifieds.

In the dusk Smooth Island's navigation light begins to blink its code name to sailors bound for Dunalley[54]