Crag, cove, and crater
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The thumblike spire at our image's right marks one of the most beloved photo ops in this landscape of barren, tawny stone. Seated right upon the shore, Pinnacle Rock is a volcanic plug made of hardened magma, the only remnant of a volcano whose cone eroded away long ago. Tour boats here in the Galápagos Islands sail past the picturesque point often, and the adjoining cove is a popular snorkeling spot. A matchless array of marine life (including the occasional diving Galápagos penguin) isn't all you'll find beneath these silvery seas: Look closely at the foreground of this photo and you'll notice a large circular patch of shallow water. That's an extinct volcanic crater, further evidence of the explosive activity that formed these isles eons ago.