Which leads to the rather bizarre situation where a petrified character, if pushed into the bay, would drown.
That, and to me "petrified" implies absolute rigidity: you can't blink, your heart stops beating, and your chest can't rise and fall so as to allow breathing.
If magic didn't exist I would agree, but in D&D land stone creatures move all the time in a fashion that defies physics.
There's also the corollary question of whether a petrified character can still see-hear-feel what is going on around it while in that state.
This is covered in the condition:
- The creature is incapacitated (see the condition), can’t move or speak, and is unaware of its surroundings.