I'm sorry, I haven't actually read the novel 'All the Water in the World', so I can't provide a detailed plot. But it might be about the various states and uses of water around the world, or perhaps it has a more metaphorical plot centered around the concept of water.
Since I don't know the exact plot, I can only guess. It could be a story that follows different characters who are on a journey related to water. Maybe they are scientists studying water, or fishermen whose livelihood depends on water bodies. Their stories could intersect and show different aspects of the importance of water in our world.
Without reading the novel, it's hard to be certain. However, it might revolve around a mystery or a discovery related to water. For instance, a hidden source of water that has special properties, or a threat to the world's water supply. The characters in the novel could then be trying to solve this mystery or deal with the threat, which would lead to various adventures and character developments.