Minecraft wiki entry for Time-saving_tips, associated text: When clearing water out from an area, a common trick is to make a drydock by dropping sand or gravel into the water, thereby displacing it, then digging all of the sand or gravel out again, leaving a dry area surrounded by a curtain wall. In sloped areas, sugar cane can do the same job as sand or gravel, but because sugarcane can only be placed on blocks which have water adjacent, the older sugar cane blocks will automatically uproot as soon as they no longer have water next to them. This saves having to dig them out as a separate stage. In deeper water, the occasional column of sugarcane can act as an airlock, making it quick and easy to move outside the dry area and float to the top level of the drydock.