luneigh is referring to the proc effect message. In game, it definitely says "sees" instead of "seas". I'm trying to find it, but I think that this is a classic typo. So far, I can't seem to dig up where I read that.
And not to divert too strongly from OP's real topic but:
As far as the text on the item icon goes, seems like it was "Song of the Deep Seas" until it was upgraded:
[You must be logged in to view images. Log in or Register.]
Then after the late 2001 upgrade, they mistakenly added "Sea's":
[You must be logged in to view images. Log in or Register.]