The final Shadow Shard zone contained the Storm Palace and Lanaruu. Before the teleporters were put in, this was far and away the most remote place you could get in the game and there were plenty of max level enemies floating around as well.
The Cascades was the second Shadow Shard zone. As you can see, it was WAY more vertical than any other zone in the game. The exit to the next zone was actually way at the top and you had to find your way up there.