Sorrow's path looks worse than it actually is. It has a narrow effect, but Dark water's effect is even narrower. That card is obsolete in every aspect. I can imagine that one instance where Sorrow's path would be benificial: in reject rare draft, Sorrow's path is a bomb. Dark water isn't. You need double blue to cast it, the only perceivable use of the card is to get to triple blue. Now, I can't imagine a use for 3 blue mana, and even if I did, if you'd have an island in place of Dark depths you'd have 3 blue mana.