My world has giant geysers. The height of these geysers oscillates over a cycle of 3 or so days.
Things you need to know:
1. There is an unknown force in the core of the planet, which exerts pressure outwards that oscillates in cycles.
2. There is a layer of water beneath the crust.
All around the world, these geyser are synchronized, going off at the same time regardless of latitude, longitude, or orientation. This is caused by the fluctuating waves of pressure exerted upon the outer layers from the planet's core, forcing the water up and onto the surface. When the pressure eventually dwindles, the water then drains back down in a process known as flushing, after which they begin to increase in height again, restarting the cycle. At their maximum, they reach a height of 2551.7 ft (777.7 m).
This is not an Earth-like planet.
What I want to know:
1. Is anything in my model even possible? Please point out any flaws in it.
2. If nothing I said makes any sense at all, how can I plausibly explain giant geysers that fluctuate the way I've described. (I might have to scrap the idea that they are synchronized) This is the worldbuilding site, so any new ideas are greatly appreciated.
3. I'm willing to scrap the idea of fluctuating pressure from the core and even scrap the layer of water.
I just want to be able to explain the geysers and they must be periodic and consistent. Any other data I have provided can be scrapped, if necessary.
Telling me that it can't be a planet is not a solution to my issue.
I'm aware that the layer of water beneath the crust rules out any possible volcanic activity, which kind of messes up a lot of things about my world that I'm still trying to figure out. Any possible loopholes for this would be greatly appreciated. (maybe like giant vertical tunnels of rock that push lava through the water onto the surface)