There are two types of Iguanas found in the Galapagos. The marine iguana is very prolific. Apparently they don't like cold water and can't stay in very long. They sit out in the sun or the warmth until they warm up and then dive in to find food. Often many of them were found on the rocks near the water's edge. You have to be very carful that you don't step on them when waling around. They only stay in the water for a few minutes. When Darwin found them he threw them in the water and saw that they swam back to shore right away.
The land iguana is more colorful; some with lots of red. Their main diet is prickly pear cactus.
Both of these species do look somewhat prehistoric to me. They are quite different and smaller than the Iguanas found in the BVI.