Ganymede appears to get various ocean layers, stacked up with levels of ice between them. The best volume of ice would be the crust, which might be about one hundred fifty kilometers (about 90 miles) thick. The bottom ocean stage may very well be 800 kilometers (about five hundred miles) https://moons50103.tusblogos.com/34974433/the-2-minute-rule-for-best-moons