Using higher pressure water will also increase the total available thrust without requiring more water. That's a lot easier to play with and increase than the a

Using higher pressure water will also increase the total available thrust without requiring more water. That's a lot easier to play with and increase than the analogous change in a rocket. > wouldn't a series of obstacle-crossing robots carrying a hose be more feasible It's possible but there's a lot of problems there too. There's all the problems of room + obstacle navigation that's vexed robotics for a while at the same time pulling a long flexible object weighing a few hundred pounds (in the case of a regular fire hose, less if you use a high pressure misting system like the post but that is still going to be fairly heavy to avoid damage) in a way that won't bind on some obstacle. All of that in a very challenging environment where any light based system is going to have trouble because of smoke and heat.