Katrina is a spooky, scary and eerie underwater explorer girl. She attends an all-girls boarding school for underwater explorers like her. She always wears a black wetsuit decorated with cobwebs, blood-red goggles, black gloves with fake stitches on them, a white, ghostly swim cap, midnight blue flippers, a dark gray snorkel, black bat wings and a green monster mask that covers her entire face. She sleeps in a spooky dorm room with five other spooky girls. But despite her scary appearance, Katrina is actually a very friendly girl.