In the early '90s, English rock critic Simon Reynolds coined the phrase "oceanic rock" to describe the school of hypnotic, swelling, neo-psychedelic, pseudo-New Age guitar music best exemplified by the late, lamented Cocteau Twins. Sigur Ros was still just a vision in the Icelandic mist at the time, but no band ever has been more deserving of this nebulous genre description.

The group first won a wider audience outside its native Reykjavik with its second album, 2000's "Agaetis Byrjun," a swirling mix of guitars that sounded like violins, rhythms that ebbed and flowed like the tides washing against the glaciers, and the haunting, high-pitched, ambiguously sexual vocals of bandleader Jonsi Birgisson. Songs barely mattered, since the sound was everything. Birgisson sang in a made-up tongue of nonsense syllables, and on the group's third album, 2002's "( )," he didn't even bother to title any of the tracks.

A dark and airless disc, the disappointing "( )" was recorded under pressure from the record company, in the midst of touring and amid an avalanche of hype, and it suggested that Sigur Ros had reached the end of the road with its unique sonic explorations. But the band sounds newly inspired on its fourth album, as well as considerably more upbeat. "Takk..." (which means "Thanks") is a set of 11 songs overflowing with indelible melodies and boasting actual lyrics. Granted, they're in Icelandic, but the sunny optimism and poetic vision of beautiful tunes such as "Glosoli" ("Glowing Soles") or "Hoppipolla" (which Birgisson says is about "kids jumping in puddles and one of them gets a bleeding nose but he's still having fun") transcend language, geographical or genre barriers, affecting the listener in the realm of pure emotion.