so the way to get the mermaid stuff is by diving. if you grab a scallop, this otter named Pascal shows up and exchanges your scallop for either a mermaid DIY or a pearl (which is used to make mermaid DIYs, they can be found on their own too but they're uncommon)
so his thing is that after exchanging mermaid stuff for scallops, he lays some "deep truth" on you and it sounds like hippie-dippie nonsense lol this one's my fave so far