A good CD of sea shanties is one I have mentioned here before, Blow Boys Blow, by A.L. Lloyd and Ewan McColl, re-issued from a 1960's LP. (According to the liner notes Frank Zappa, of all people, was fascinated by it.) The pace at which they sing these is often different from what you hear sung nowadays. Most sea shanties now are sung faster than these two fellows sang them -- I don't know the mechanics of it but I suspect the sailors would get very tired very quickly if they worked at such a pace.:)

Incidently, some of the lyrics on this CD would not be considered suitable for schoolchildren by many, although I imagine parents who are into folk music would explain to their children the historical context of such songs. Lloyd and McColl sing a most un-PC version of Congo River.