This guy belongs to a species of amphibious people living underwater in the North Sea, off the coast of Holland.

There are about 40000 of these people in all. The species was accidentally released into the sea by aliens, and within a couple hundred years, evolved to resemble the dominant species of the region (humans) in appearance and culture. As a result, they speak Dutch and have similar cultural practices.

Human authorities discovered the water people around 40 years ago, but avoided contacting them and kept their existence a secret. Now, however, the water people are running out of fish to eat (they're an invasive species!) and are starting to discover the existence of humans. They hope they can join humankind and get out of their unsustainable situation.