Pinnacle Rock, is a celebrated volcanic plug on Bartholomew Island, one of Ecuador's Galapagos Islands. It is Sullivan Bay, part of a channel that separates Bartholomew from nearby Santiago Island. The rock is part of a now largely eroded volcanic dike that once connected the two islands. Travel writers describe the rock as one of the most spectacular views in the Islands. A colony of penguins makes its home at the foot of the rock. Tourists dive in scenic reefs offshore of the rock.