The Gen 5 Mane Six find a secret entrance under the Brighthouse that leads to a secret subterranean world under Maretime Bay. It’s where they meet new sea creature friends called Nessies. Together with Happy Ness, Queen of Happy Land, and a bevy of delightful sea creatures they embark on a series of amazing adventures.

Crossover of My Little Pony: Generation 5 and Happy Ness: The Secret of the Loch

(Note: This story is an inspiration to ShopperBrony90 since it was his idea of crossovers that inspired me to make this, so give credit to him.)