Piratecat's spoiler warning also applies to this post, and is extended to cover Wulf Ratbane's story hour, and the other WotC modules.
As Wulf said, yes, it is. Deep Horizon is the sixth in the series of eight, and is for 13th level characters.
As for Wulf's difficulties -- I've read the story hour, and read the modules, and Dinkledog seems to occasionally . . .
enhance the experience, shall we say?
For example, Wulf's latest posting reports an encounter that seems to have a couple of extra batguys. And Forge of Fury didn't have any drow, and the orc bodycount seemed double the adventure's.
Note that I'm not saying there's anything wrong with that; I occasionally beef up the adventures, too (buff characters from my powerhungry mob o' players, plus a large group), though I usually just make the individual critters tougher (stats & hp above average, thus better matching the PCs; shh, don't tell my players ;D).
Plus, Dinkledog's dice roll well at (in)opportune times. Me, I roll strings of 20s for goblin goons, but the dragons are always rolling to avoid fumbles.