Verbal components don't work if you are gaged so following that logic they would not work underwater either. Maybe for underwater races with water breathing that learn the verbal parts of their spells in a way that works underwater.
As far as how it would effect the spells themselves, no info yet till DMG but traditionally I think lighting spells become spheres around the caster, wind magic doesn't work, and as noted in the underwater combat section anything underwater has resistance to fire damage.
As far as how it would effect the spells themselves, no info yet till DMG but traditionally I think lighting spells become spheres around the caster, wind magic doesn't work, and as noted in the underwater combat section anything underwater has resistance to fire damage.