My old, WW II era diesel boat leaked about 10-15 gallons a minute at periscope depth (60 feet). At test depth (400 feet) the leaks dropped to a few gallons a minute.
You sound like someone who can answer a couple of questions. The sub surfaced, so why didn’t they send out their coordinates while communications were still up and remain at that location until rescued? Don’t subs naturally float but have to be forced to go underwater?