How do you learn how to swim without water or a pool? We are going to a waterpark but I don't know how to swim and I don't have a pool. I also don't have time to go to the pool or somewhere.
There are sad photos of people during wartime and economic depressions taking swimming lessons on land, with swimsuits on, balanced on pieces of wood or the like. Unfortunately, you'll make little progress in this way. The main things to overcome are comfort in the water and then taking advantage of breath holding, balance, and floating for efficiency. There is nothing to replace practicing in water.
One thing you can do at home is to practice submerging your head in cool water and holding your breath for a few seconds, and then recovering after raising your head. If you do this with water that is warmer than the water park will be such as bath water, you may not trigger the same instincts and fears we are all born with.
If you are scared of water, you should only stay in areas of the park meant for novices. Kids slides and shallow pools with only gentle waves or currents. Breathing in water accidentally if you are not comfortable can become very dangerous for you and those around you, even after you leave the water. Read up on dry or secondary drowning.