Seems like a normal distance to me. Not the alleged almost collision that the Italian newspapers would lead you to believe.

Does it get dicey towards the end as she’s turning to port, eh maybe.

But as COLOREGS (link in PDF), the rules-of-the-road at sea, state, you must always give way to the larger vessel. That would be the Carnival Sunshine. And the Vaporetto drivers need to yield to her and not come flying up on her stern all haphazardly.

thanks @CruiseGuy for the video