Finn is a muscular merman with cyan skin, dark cyan fins, and green eyes.
Finn is not much of a talker, to the point he broke up with Lorna by text message. Given he was rather well-dressed for his one appearance, he might be of a well-to-do family like Lorna.
In "Looks Gil-ty", Finn and Lorna were getting help from Gil in how to deal with their parents because, like Lagoona and Gil, Finn is saltwater and Lorna freshwater, as Loch Ness, being a lake, is a freshwater area. Despite the help, he broke up with Lorna in "Gloom and Bloom, Part 1".
- January 29, 2015: Finn makes his 2D debut in the webisode "Looks Gil-ty".
- Since it is only spoken, it isn't clear how Finn's name is spelled.