The map is calling the Cutie Mark Crusaders to Mount Aris for a friendship problem. It is their first and the first time the map has called some pony creature to a place outside Equestria. It’s either been Ponyville, Canterlot, Manehattan, or where the Pony of Shadows hung out.
Twilight is coming along for
an excuse to visit Mount Aris since the events of the movie research and to get Silverstream’s parents to sign a permission slip so she can go on field trips (shouldn’t that be Silverstream’s job?) They come across Silverstream’s brother Terramar who can’t decide between living on land as a hippogriff (like his father Sky Beak) or in the sea as a sea pony (like his mother Ocean Flow). This being Hasbro, they are not going to mention that the parents are separated/divorced. (Is it only Arthur who really goes that far?)
The CMC get a tour of Mount Aris and Seaquestria and Sweetie Belle is in love with Harmonizing Heights on Mount Aris while Scootaloo enjoys Seaquestria (while Sweetie Belle does not). That doesn’t help Terramar with his problem which he believes he needs to choose between the two. Actually, no hippogriff or pony told him to choose and Terramar’s parents realized that he shouldn’t be compelled to choose either and he can go back and forth.
While fans may not appreciate Hasbro possibly going end around with the parents living separately, they do establish that some of the hippogriffs got used to the sea while others returned to Mount Aris after the defeat of the Storm King. In the case of Terramar, it splits down his family. There does not seem to be any animosity between Sky Beam and Ocean Flow, and there are ways hippogriffs can go back and forth as the magic pearl has been split and distributed throughout the realm.
I guess Twilight has been forgiven for trying to steal the pearl in the movie as she is treated like a celebrity here. Of course, the bar is low for forgiving characters here.
Overall, this is a very good episode, though some may find some aspects a bit off. Terramar, Sky Beak, and Ocean Flow seem like nice characters and we get a decent bit of world building.