Sinker cypress wood consists of cypress logs that have been submerged in rivers or swamps since the late 1800s. The logs were cut by axes or hand saws from 150- to 1500-year-old virgin forests during the “industrial cypress harvest” from 1880 to 1930. The fallen logs were then taken to the nearby rivers by oxen or horses to a neighboring riverside sawmill. During their trip down river, it was common for some of the logs to become waterlogged, or get stuck in a log jam, where they would sink to the bottom of the river. They have been preserved underwater since that time.
Today, the sunken logs are retrieved by divers, raised to the surface and shipped to a sawmill where they are cut into different lumber sizes and allowed to air dry. The required drying time is usually one year per one inch of thickness of the lumber. If a kiln is used to dry the lumber, then less time is needed for air-drying. Typical drying periods range from 1 to 2 years after the log is cut into lumber. This allows the wood to dry slowly and become more stable and resistant to warping and exterior elements.
"How to Become an Interior Designer" by: Lewis Parrott