As soon as he heard we were in Indonesia, Stephan Kempe started telling us about his work on Satonda Island and when I got the invitation to talk at Universitas Teknologi Sumbawa (UTS), I knew we had to find a way to visit. UTS invited both Tim and I to speak and were enthusiastic about him including the geo-history of Satonda Lake in his talk which gave us even more reason to go.
And I am so glad we did!! It's not really possible to explain how really, freakin' cool it was to experience Satonda Lake.
It is a crater lake that was formed by the eruption of Gunung Satonda (which is described as a "parasitic cone" of Tambora). It was first a freshwater lake (and has remains of the peat bogs that it originally supported) and later filled with sea water. But (I think I have this right), after the enormous 1815 eruption of Gunung Tambora (on Sumbawa), there was uplifting and the connection to the ocean was closed off. The lake has since become hyper-saline and alkaline (pH 8.5-8.6) and has, essentially become a window into the origins of life: there are only a few species that can survive in the warm, extreme conditions, and it is now one of only a couple places on Earth that still have living stromatolites. These are one of the oldest extant species and their evolution kicked off O2 production on Earth, changing the composition of the atmosphere and allowing heterotrophs to evolve. So cool. To swim there is, essentially, like going back in time and swimming in Earth's ancient oceans.
Stephan and his co-authors have documented the stomatolites, algae, a couple of species of sponges (also living fossils), some snails, and a single species of fish (I thought I saw two, but maybe the young just have a really different morphology).
The water is really warm, and really buoyant. It was almost impossible to get photos because you floated up so fast after diving down.
We swam clockwise along the edge to about the halfway point across the lake and then straight back through the middle. Because of the high calcium carbonate load (I think), the water is a strange milky blue and it was kinda freaky to be swimming over water that deep (nearly 70m) with visibility of only a foot or so. And I gave myself a blister from one fin (I've never gotten one before) and had to carry my fin in my hand the whole way back, so the swim 'home' was a long one :-( But worth every second of it.
It is a crater lake that was formed by the eruption of Gunung Satonda (which is described as a "parasitic cone" of Tambora). It was first a freshwater lake (and has remains of the peat bogs that it originally supported) and later filled with sea water. But (I think I have this right), after the enormous 1815 eruption of Gunung Tambora (on Sumbawa), there was uplifting and the connection to the ocean was closed off. The lake has since become hyper-saline and alkaline (pH 8.5-8.6) and has, essentially become a window into the origins of life: there are only a few species that can survive in the warm, extreme conditions, and it is now one of only a couple places on Earth that still have living stromatolites. These are one of the oldest extant species and their evolution kicked off O2 production on Earth, changing the composition of the atmosphere and allowing heterotrophs to evolve. So cool. To swim there is, essentially, like going back in time and swimming in Earth's ancient oceans.
Stephan and his co-authors have documented the stomatolites, algae, a couple of species of sponges (also living fossils), some snails, and a single species of fish (I thought I saw two, but maybe the young just have a really different morphology).
The water is really warm, and really buoyant. It was almost impossible to get photos because you floated up so fast after diving down.
We swam clockwise along the edge to about the halfway point across the lake and then straight back through the middle. Because of the high calcium carbonate load (I think), the water is a strange milky blue and it was kinda freaky to be swimming over water that deep (nearly 70m) with visibility of only a foot or so. And I gave myself a blister from one fin (I've never gotten one before) and had to carry my fin in my hand the whole way back, so the swim 'home' was a long one :-( But worth every second of it.
We also hiked up to the crater walls (scrubby forest with a lot of butterflies) and looked back down at the lake. You could see the stromatolite mounds even from up there.