Madaket Ditch is like a big, long path that was made by people in the ground. It's kind of like a river made out of dirt instead of water. People made it a long time ago so boats could go through it instead of going all the way around the island.
When boats go through Madaket Ditch, they have to be really careful because it's not very wide and it's shallow in some places. Sometimes, big boats have to wait for the tide to go up so they can float through the ditch without getting stuck.
People also like to go fishing and kayaking in Madaket Ditch because it's a cool way to explore the island and see all the different kinds of plants and animals that live there.