After album (or "observation," as the band likes to call them) number eight -- Ghost Reveries -- Opeth could have very easily coasted, merely rehashing their sound.

Instead, they opted to challenge themselves and their listeners, creating an album that can -- at times -- expose its true nature and scope slowly and -- at other times -- be jarring, as if it were turning itself inside out.

Opeth take chances that many bands in the same situation would be too scared to have a go at.

It's hard to say if the recent membership changes affected bandleader Mikael Åkerfeldt's writing and production, or if he was enjoying his trip down classic rock (see: Deep Purple) lane.

For whatever reason, Watershed is a new benchmark for Opeth.

The tricky part is pointing out that while Watershed is a fantastic record, one that takes chances while remaining totally metal (dude), it feels less like a complete statement than a preview for something even greater.

After the pastoral introduction of "Coil," Opeth move into pummeling mode with "Heir Apparent." It's one of the few tracks here to feature growling death metal vocals.

But it is track three where Opeth really take the listener by the ear and twist.

There's a gently humming prologue, then "The Lotus Eater" becomes a slab of blastbeats iced with clean vocals that -- as with many Opeth tunes -- takes a "break" two-thirds of the way through, only to take one hell of a left turn out of nowhere.

The tune doesn't just go back to heavy riffage, but explores a prog metal, psychedelic organ quasi-freakout that touches on pure jazz.

"Burden," arguably the strongest of the classicist tunes on Watershed (closely followed by "Hessian Peel"), is lush and grandiose.

It's the moment on this collection where the listener realizes how incredibly talented this band is.

And if the songs themselves aren't enough, the structures and fade-outs on some of them are.

An example: "Burden"'s gentle guitar outro is deconstructed by someone manually detuning Åkerfeldt's guitar as he plays.

Another: "Lotus Eater"'s Dark Side of the Moon-esque "voices in your head" send-off.

These add more depth to an album that surprises continually, even after repeated listens.

Sure, there are some (sort of) weak moments -- "Porcelain Heart" seems a bit mainstream, and "Hex Omega," while a stunning closer, has insanely tough competition as a standout from the other six tracks.

Essentially, Opeth's perceived weaknesses would be pivotal moments for any other band.

This is a band that has managed to get exponentially better with each release, taking amazing chances and managing to not only win new fans, but not alienate older ones.

A perfect blend of the death metal of Still Life, Blackwater Park, and My Arms, Your Hearse, the monolithic riffage of Deliverance and Ghost Reveries, and the prog/classicism of Damnation combined with classic Deep Purple, Pink Floyd, and Scorpions, Watershed marks a new chapter for Opeth, one that promises infinitely more than its predecessors.