On this walk I had a second camera with a short lens with me. Even before leaving the house I knew the day was going to be magnificent. It was. Clear sky, mild(ish) temperature, slight breeze meaning few bugs.
I stopped to get a few wide shots on this dike. Huge marshes are on both sides with several wooden trunks to move the flow of water between them.
Below the water feeds into a canal that pushed water forward and back to open wetlands. Of course a few floating heads can be seen if you view the image large. Saying they are everywhere here is no exaggeration.

The left side of this dike, below, is also wide open marsh lands. The trunk gates you see move the water through the dike. Flow direction is ultimately controlled by the ocean tides miles away. We are very, very, flat so water moves a long way.

Just an FYI; gates on these trunks are not lifted up to let water move. The solid wood gate is actually push out and away from an opening. It is pushed just enough to let the top of the water follow the natural direction. Fresh water is lighter than salt, and floats atop the brackish tidal water.
Only the top fresh water is allowed to move around the marshes. Hundreds of trunks, with the fresh water move through dikes between marsh after marsh.
When rice was the main plantation cash crop enslaved people from Barbados, and later West Africa, taught planters how to control fresh water with trunks. We still use wood, build them the same, and many are still in the same location 300+ years later.
Bear Island, South Carolina.