Satonda Island

Satonda is a small volcanic island off the northern coast of Sumbawa near Tambora, and inside its crater is a lake of salt water that is not simply seawater: it is markedly more alkaline, with a chemistry that researchers have compared to the oceans of the Precambrian, and it supports microbial communities and carbonate structures that make it a scientific reference site rather than merely a scenic one. How the salt got in is debated - a tsunami from the 1815 Tambora eruption is one explanation, seepage another. The lake is ringed by forest with flying foxes roosting, and there is a wishing tree hung with stones on the shore. The reef outside the crater is good and liveaboards on the Komodo route stop here. There is no accommodation on the island.

The landscape

• An alkaline crater lake - saltier and more alkaline than the sea outside.
• A Precambrian analogue - microbial and carbonate features studied as ancient-ocean parallels.
• Flying fox roosts - the colonies in the forest round the crater rim.
• Reef outside the crater - snorkelling and diving on the way past.

When to go

May to September. A day.

Things to know

There is no accommodation and no facilities - it is a day stop from a boat. Swimming in the lake is restricted in places to protect the structures. Access depends entirely on charter or liveaboard.

Nearby

Tambora is on the mainland opposite; Moyo island is west along the coast.

Key facts