Where is Strake going? I don't know, but he wants to get there fast.

I wasn't sure exactly how a dolphinsynth swims, but one part that seemed obvious was, it'd be the tail's job (or really the whole body's, in that sort of undulating motion dolphins do) to propel him forward, and the arms would then only be used for control. That means there's two obvious options for the arms' pose, either a superhero flight pose with arms forward, or this, and this one seemed more aesthetically interesting.

Art by  M.a.o who's trying to build an audience, so go and fave her upload. Synths and their wonderful design flexibility by  Vader-San.