Thiessen Polygons From Polygon Input

Discussion created by eric_s on Aug 5, 2010
I'm stumped.  I have a map of watersheds of the United States:  complex polygons tracing across the US that all meet the ocean eventually.  I want to buffer these polygons a few km into the ocean.  A Buffer operation will buffer each polygon individually, creating overlap.  I can't have this.  What I'd like is a sort of Thiessen bubble effect only where no polygons exist (the ocean).  The Create Thiessen Polgons only accepts point inputs.  There are hundreds of watersheds so I can't do this manually.  What can I do?

I'm using ArcInfo license on ArcMap 9.3.1 SP2.

Attached is a visual of what I'm looking for (made in Photoshop).