This is obviously not a guitar song, but as close as I can get to it is this.

Verse, i.e. 1

G.         C D  G        B
I believe, submarines (backing  vocals)
G.          C    D    G.   B
Underneath, deep blue sea (backing vocals)
G.            C. D  G    B
Saw the flag, Japanese (backing vocals)
G.           C   D.  G.  B
No one will, believe me (backing vocals)

Chorus I.e. Chorus 1

Em.                       D.     G
Ran back to the town folk and I told the people how
Em.                 D.     C. 
I've seen a submarine and everyone laughed and laughed

And then back to normal. It's pretty much just that the whole time, but I apologise for any lyrics that ate wrong