An interesting snippet on Pakistan’s nuclear policy (from indianpunchline.com, which I have no prior experience with):

Pakistan’s nuclear doctrine allows for first strike if the nation’s survival is deemed to be under thereat. Three thresholds have been spelt out: denial of water flow into Pakistan (under the Indus Waters Treaty); any naval blockade; and foreign occupation of Pakistani territory. 

India has unilaterally suspended the Indus Waters Treaty. I have however seen articles arguing that they do not have the technical ability to deny water flow on a significant scale. Still, even if this is all just talk at the moment, it is a step down a dangerous path for the region and the world.

Being fairly ignorant of geography, I had to review how much coastline Pakistan actually has. And it does in fact have a substantial coastline on the Arabian Sea/Indian Ocean, with a Karachi as a major coastal city.