There are literally hundreds of choirs who have performed this

Here is another audio file of the song, with harp

http://www.muc.muohio.edu/~choralier/music/Roll_of_the_Sea-Loomer.mp3

And another

http://www.coc.cc.ca.us/departments/MUSIC/Music%20Clips/Roll%20of%20the%20Sea.mp3

Allister MacGillivray's web-site