When Modest Mouse, a once obscure, once indie band, cruised onto the mainstream in 2004 with their hit “Float On,” they were instantly embraced by the pop-loving masses. Their new album is sure to be just as widely accepted, but possibly by a different type. On this sixth album, they stray from commonplace pop and opt for a more eccentric, offbeat sound that will please both mainstream listeners and indie lovers. The reason for this reform may be triggered by the addition of Johnny Marr, ex-Smiths guitarist. Or it could be Modest Mouse’s strange fascination with all things nautical, which creates the obvious premise and overall vibe.

In addition to the title, this oceanic theme is immediately seen in the first track, “March Into The Sea,” a song complete with all the boozy swagger, throaty anger, and brash sound that you expect from a raucous ship’s crew (embodied in five northwestern indie rockers and one middle-aged British guitarist, of course).

Like most bands today, Modest Mouse takes a stab at the government in the form of apocalyptic imagery that explodes bitterly throughout the album. None of the songs that toy with the dire state of the world is more profound than “Parting of the Sensory.” In a rare moment of sentimentality, Isaac Brock - singer, lead guitarist, and assumed captain of this ship-gone-awry - ditches his usual embittered growl for a genuinely dreamy croon (or as close to a croon as one can get with such a naturally annoyed voice). His heartbreaking chants over hauntingly simple strings and an echoing drumbeat hit close to home. They make you wonder if the apocalypse really is upon us, or at least a governmental catastrophe.

But don’t think this album is all doom and gloom. Despite its ironically serious lyrics, the first single, “Dashboard,” is a sugary melody infused with a driving disco beat and fluid, buoyant guitar rhythms. Another track that characterizes the jaunty pop rock that flung Modest Mouse onto the map is “Florida,” in which James Mercer of the Shins graces the chorus with his high-flying but serene vocals. This is a welcome cameo and is both a nice balance to Brock’s gut-busting bellow and a good accessory to the easy, sing-along beat.

Another standout track is “Spitting Venom,” a jagged, eight-minute-plus anthem that epitomizes each musical style Modest Mouse experiments with. The song starts off as a jerky folk ditty. Then the guitars come in, addled and demanding, and the song morphs into a swaying melody where Brock favors his regular grunt. In a matter of minutes, the gifted frontman transforms from wise storyteller to husky street preacher, showing his uncanny ability to captivate an audience with these addictive anthems.

The title alone, “We Were Dead Before the Ship Even Sank,” perfectly describes what this album is about: a boat trip gone bad and the destruction of society. It’s pretty heavy stuff, but no one but Modest Mouse could make the end of the world sound so good.