To me, if it didn't have the origional crew in it somewhere, it just wouldn't be The Dig.
Also, as strange as this may sound, there is nothing else on Cocytus besides the island. It says in the strategy guide that ages ago the polar ice caps melted from a solar flare leaving nothing but the island standing. The island and spires were the top of the tallest mountain on the planet so they were spared. The book contradicts this at one point and says something about other continents as a passing mention.
"I am not afraid of you, you hairless monkey."~Ludger Brink