That turtles really looking good Dave! Also, I'm guessing the volumetric effect is coming from a fluid container? Have you fiddled around with parti_volume? Anyways, an mia mat with an ocean texture for displacement would do the trick. I mean, you can setup fresnel reflections with Maya standard shaders and a sampler info but why bother when you can just tick a checkbox on a physical shader like the mia_mat(I think there's a water preset too).