The Hawaiian singer-songwriter Jack Johnson redefines "benign". It's hard to muster up strong feelings about his unassuming folk-pop – except perhaps amazement that it sells at such a furious pace. Like waves in his beloved surf, Johnson's songs tend to come and go without leaving much individual trace. His lyrics are scrupulously non-specific, but one guesses that To the Sea, his fifth album, pays tribute to his surfer father Jeff, who introduced Johnson to maritime pleasures, and who died last August. As ever, the results are perfectly nice, with no unsettling emotions to trouble the water.