Problem with vertices

Hello, I’m having problems building my character:

No idea why his fins look like this. Although I’m following a tutorial, what I’m doing is no part of it, so I have no idea why this is happening.

Not sure what else to add.

I hope a solution soon, thanks.

Hi Mr.
could you provide the scene? The things I see at the moment are some topo problems like a lot of triangles you dont need. Lots of hard edge angles you dont need too and some ngons that are unnecessary … about the fin… maybe there is some useless extra geometry or crazy normals or edge creases…

Ensure you have consistent face normals.
Select all vertices and remove doubles (W / remove doubles)
Select all vertices and recalculate normals (Ctrl+N)

Edges with 3 faces connected to them mess up the normals