I was wondering that. I'm not sure. If there is a hole, the things that matter are the outside pressure and resistance to water flow. The latter is mostly visc

I was wondering that. I'm not sure. If there is a hole, the things that matter are the outside pressure and resistance to water flow. The latter is mostly viscosity I'd think and very little to do with air pressure on the inside. Whereas water pressure is 3x surface. That said 19m is really not that deep, I don't think it would be dramatically different to a leak closer to the surface. Some ships have draft of like 15m and, while generally holes in hull are bad, I'm not sure that this is some kind of special design precaution. But I wouldn't really know.