Satonda Island

Satonda is a small volcanic island off the northern coast of Sumbawa, and it holds one of the more unusual bodies of water in Indonesia: a salt lake inside its crater.

The crater lake sits just metres from the sea, separated by a narrow rim, and its water is saltier than the ocean around it. The widely accepted explanation involves Mount Tambora, 60 km away, whose 1815 eruption — the largest in recorded history — generated a tsunami that washed over the crater rim and filled the lake with sea water. Evaporation since then has concentrated the salt further. The lake also contains unusual carbonate structures built by microbial life, which researchers have studied as an analogue for very early Earth conditions.

A short walk from the landing beach brings you to the lake shore, where a tree is hung with strips of cloth and stones left by visitors making wishes — a local tradition that has grown considerably over the years.

The island is uninhabited and forested, and the snorkelling off the beach is genuinely good, with a reef drop-off close to shore.

Like Moyo, Satonda is visited almost entirely as a stop on the Lombok to Komodo sailing route. There are no facilities, no shop and no fresh water — everything comes from the boat.

Why is Satonda's crater lake salty? The most widely accepted explanation is that the 1815 eruption of nearby Mount Tambora generated a tsunami that washed sea water over the crater rim, with evaporation concentrating the salt since.

Where is Satonda Island? Off the northern coast of Sumbawa, between Lombok and Flores, on the Lombok to Komodo sailing route.

Can you swim in the Satonda crater lake? Yes — and the high salinity makes you noticeably more buoyant than in the sea.

How do you get to Satonda Island? Almost exclusively as a stop on a multi-day sailing trip between Lombok and Komodo, as there is no scheduled service.

Is there snorkelling at Satonda? Yes, and it is very good — a healthy reef drop-off sits close to the landing beach.