The Dink Network

Are you using Redink's script? Because that bit is basically the same as what you put above:

&count = random(10,1);
if (&count == 5)
{
  playsound(35, 16000, 0, 0, 0);
  spawn("splash");
  //that just makes the splash graphics
}
wait(100);

So I'm not sure why your sound doesn't work unless there's something wrong with the sound itself... does it work when not in this loop?
Or perhaps the script is going wrong somewhere else - there are 5 or 6 different loops in it to get tangled up

To do that walking through water I think all you need to edit is the x/y positions of where Dink actually enters the water and it should work fine.