This song is on the chillout half of the 22-track release "Sonorous Susurrus" by K.I.A. See also the K.I.A. songs "Mmm" and "Uneunoia" for a similar downtempo/ambient vibe.
This artist also records as Shinjuku Zulu. For more downtempo tracks similar in mood to "Dubmarine", check out "Coal Coal Black" and "Rainbowbeau" from Shinjuku Zulu's "Various Chimeras" 19-track release.
All songs on iTunes.