Also, the pumps have to be at the lowest point, pushing the water up - a siphon has a maximum height that a vacuum can draw water up of around 10m.[0] You can't

Also, the pumps have to be at the lowest point, pushing the water up - a siphon has a maximum height that a vacuum can draw water up of around 10m.[0] You can't just stick the pump at the entrance and then shove a pipe hundreds of meters down the cave system, you need to take the pump down there and run the hose back to the outside. 0. https://en.wikipedia.org/wiki/Siphon https://en.wikipedia.org/wiki/Siphon