• Scientists believe that millions of years ago, land-dwelling iguanas from South America drifted to sea on marine litter and eventually reached Galapagos. There they evolved into marine iguanas and spread over the entire archipelago.
• They are the only sea-going lizards in the world and they can remain submerged for about 10 minutes at a time!
• They are about 0.6 to 1.5 meters long. That is about 4 to 10 average-sized ball pens placed one after another.
• Even though they look scary and a bit dangerous, these iguanas are actually herbivores that feed on underwater algae and seaweed.
• When there is a shortage of food, the iguanas not only become thinner but also shorter. Scientists have discovered that iguanas can grow back to their normal size when their food supply increases.
• Their dark grey colour helps absorb sunlight and after they collect enough energy they go swimming in the cold Galapagos waters.
• They sneeze quite frequently to remove extra salt that they consume while eating.
• These iguanas are found only on the Galapagos Islands. And even though they are called marine iguanas, they are amphibians.

Sources:
Discover Wildlife
National Geographic
WWF
BBC