You and a/some friend(s) where exploring the city, when soon you came across an abandoned warehouse, growing curious you and your friend(s) went into the warehouse. Soon you tripped over what you guys later found out to be a door in the floor. You and your friend(s) grew curious so you opened it and went downstairs, it was many stairs down, at least 10 feet below the street level. It was dark, but there were a few blue lights along the way, it was a bit creepy at first. Soon you found a large cylinder tank though, it was about 9 feet (3 meters) high, a deck around the top with a guard rail around the whole thing except for a gate so that someone could get the creatures out of the tank if needed. It was around 15 feet (5 meters) in diameter, you and your friends looked carefully into the water, and soon you saw hiding in some of the rocks in the tank, a tail, then a head peeled over the rocks a bit, it was a merman, and he looked a bit afraid, but also curious. What do you and your friends do?

(It can be just you as well, you don't have to have friends with you, it's all up to you.)