“300: Rise of an Empire” won’t disappoint fans of the first blockbuster (“300”). The visceral visuals that drove the first ferocious retelling of the ancient battle of Thermopylae—in which King Leonidas and 300 Spartans fought to death against Xerxes and his massive Persian army—have been ramped up, opening a new chapter in the bloody, epic saga of the proud and fragmented Greek nation’s struggle for freedom.

The new battlefield is the unruly and unforgiving sea. This new installment is directed by Noam Murro, taken from a thoughtful screenplay by Zack Snyder and Kurt Johnstad, based on the graphic novel “Xerxes” by Frank Miller.

The battle-weary navy general Themistocles (Sullivan Stapleton) stands bravely against the bloodthirsty Persian forces, ruled by the mortal-turned-god Xerxes (Rodrigo Santoro) and led by the vengeful navy commander Artemisia (Eva Green).

It’s not a sequel in the traditional sense. It takes place during the battle of Thermopylae, where the doomed, landlocked Leonidas faced the Persians at the Hot Gates.

Driven by one certainty, Themistocles knows that a slender thread of hope rests on uniting all of Greece, a task almost as challenging as surviving the advancing Persian warships.

Murro’s sturdy hand massages the best work from director of photography Simon Duggan and editors Wyatt Smith and David Brenner. The team delivers fleshed-out characters whose deep wounds and fierce loyalties help shape the story arcs, resulting in a fuller experience, and because the action-packed film is being released worldwide by Warner Bros. Pictures in 3-D and 2-D, it’s more than just a popcorn flick.

Brazilian actor Santoro, as the transformed Xerxes, is one of the finest actors working in the world. Simplicity flows into complexity; this masterful craftsman is able to convey volumes of emotion with a single glance. Green, who breathes fiery life force into the psychopathic war general Artemisia, delivers a performance as complicated and impactful as one of Beethoven’s symphonies.

“300: Rise of an Empire,” which opens March 7, is an epic adventure wrapped in a human story.