Very simple Bass line to a great track from UB40s Cover Up album:

Play Throughout,The changes are simple!
Verse:
G:--------------------------------------------------------|
D:--------------------------------------------------------|
A:-55-5----55-5--22-2----22-2--55-5----55-5--22-2----22-2-|
E:--------------------------------------------------------|

Bridge:(to Chorus which is the same as Verse)
G:--------------------------------------------------------|
D:--------------------------------------------------------|
A:--------------------------------------------------------|
E:-33-3----33-3--00-0----00-0--33-3----33-3--00-0----00-0-|

You can play a few fills & mix between octaves for fun?
(& for Guitar Reggae chop,D,Bm,G,Em.)