Oh god, this one is really really bad. Just to explain what she says in the japanese version, she was supposed to say that the sea was enjoyable (tanoshii), but she replaced the shii part with the sea, which sounds similar in japanese, making a terrible pun with it.
劇場第534『アンニュイ楓』
Theater Episode 534 - The Melancholy of Takagaki KaedeSlump...Sea is so... Amaseang......SeaAh... Kaede-san...As I thought, Kaede-san is so amazing... Mayu wishes she could be like that too...