How to sing My Bonnie Lies over the Ocean in your key
My Bonnie Lies over the Ocean spans 12 semitones (B3 to B4 in its usual key), 34 notes. That's an octave or less, so it fits most voices once it's in the right key.
Words
My Bonnie lies over the ocean,
My Bonnie lies over the sea,
My Bonnie lies over the ocean,
Oh, bring back my Bonnie to me.
Finding your key
A song is in your key when its highest note sits at or just below the top of your comfortable range. Measure your range, then move the melody so its top note (B4 here) lands one or two semitones under your easy top. Singsteady does this for you and scores every note as you sing.
traditional Scottish, published 1881. Melody and words are in the public domain. Notes transcribed from the score in Wikipedia, “My Bonnie Lies over the Ocean” (score).