For whatever reason, there are many recorded live performances of Castaway where Green Day plays it a half-step up from the key of the original recording (B major). Maybe Billie just likes challenging his voice. It’s more likely, however, that they got used to playing it a half-step position up since their guitars were probably tuned to Eb (like the guitars on most Green Day albums), and then in the future when they started using different guitars that had different tunings, they were already used to playing it in the half-step up position, which caused them to subsequently start playing it in C. This probably doesn’t interest anyone, but…you know…just saying. It is also purely speculation.

The chords below are assuming you are in standard tuning (like the guitars used on the Warning album) and want to play it in the same key as the recording. Have fun!

Castaway chords and lyrics

Also, here is a pretty sweet live performance of Castaway. Notice that they appear to be playing it a half-step up (starts on a C on the 3rd fret, which is actually a B since they’re tuned town a half-step).