Does having water up to your shoulders affect your voice and singing ability?
It would have a small effect on the effort needed to inhale (increased) and exhale (decreased).
Other than that, probably not much - but I await better-informed posters.
Never tried singing while up to my shoulders but it makes sense that the exhalation would be aided, which is a plus when singing. Breath support is a huge part of singing, and being submerged would, I think, act to increase the effective strength of the diaphragm. However, it would probably take a little practice to get used to it. Being submerged would not otherwise affect the tone of your voice or intonation.
It depends which part.
The coda of Nearer My God to Thee.
Is this an Esther Williams question?
Your vocal folds are in your larynx, which wouldn’t be underwater if you’re submerged to your shoulders so it doesn’t seem likely the sound would change, just your ability to inhale as mentioned previously. But even that wouldn’t be affected much unless you’re a giraffe submerged to your chin- your lungs and diaphragm won’t be very far below the surface, so the pressure from the water won’t be all that significant, either.
Win!
And how cold the water.
Depends if you’re a mermaid.