How far can warship subdivision go?

What is the extreme end of subdivision, and how small a ship can use it?

Compartments can be made extremely small, but the useful limit is reached when access and operation become impractical; ordinary subdivision is possible on nearly any seagoing ship.

Almost every seagoing ship uses some subdivision, but extreme compartmentation can reduce spaces to the dimensions needed for one item of equipment or a very small service area. Such density may improve survivability in theory while making maintenance, movement, and ordinary operation increasingly difficult. The practical limit is therefore set by how sailors and machinery must use the hull, not simply by how many bulkheads can be drawn.