Outside of Canal Exploration Center is a reconstruction of Lock 38. On summer weekends when conditions allow, volunteers demonstrate how a lock operates. Canals were designed as waterways without waterfalls or a current. Locks were built to raise or lower canal boats wherever there was a significant change in elevation. A lock works much like a toy in a bathtub. If a boat needs to go up, water is let in through butterfly valves in the upstream gate. The chamber is filled until it is level with the upstream water. If the boat needs to go down, water is let out through butterfly valves in the downstream gate. When the water is low enough to match the downstream level, the downstream gates can be opened. To fit inside the locks on the Ohio & Erie Canal, boats could be no more than 75 feet long.