Today we anchored "in" an island. You may wonder how this can be, but in the Galapagos everything is possible. The caldera (main crater) of this old dormant volcano has collapsed leaving an entrance behind. This is what allows us to enter the summit of this island with the Polaris.
Calderas are roughly circular collapsed depressions found near the summits of many volcanoes. They form above magma chambers, which are large regions perhaps 2 to 5 km. down, where the magma often accumulates as a staging area on its way to the surface. They are the direct result of the instability of these chambers. If the chamber roof is circular, as the magma rises, the fractures produced will be broadly cylindrical. Subsequent removal of magma from the chamber by eruptions removes support for the overlying cylinder of roof rock and it drops into the newly vacated chamber. As a result we end up with a huge depression or caldera.
This photo shows the Polaris inside one of these calderas. In this case, Genovesa´s caldera is about 2 km. in diameter! It also demonstrates what the island looks like in the radar and the depth finder, showing the depth when we cross over and out of the caldera.
To enter and leave this caldera our captains have to maneuver very carefully, as at one point the ocean bed rises to 7.5 m. This is only 24.6 feet! Because of the expertise and experience of our captains we are confident, certain and secure in anchoring "in" this island.
