Canal lock construction works on the same principle as moving between levels in a house, except the water levels become the stairs. Two sets of large whaler gates contain smaller wicket gates. The large gates help hold the boat in place while the wickets control the water level. Although northwest Ohio may seem flat, there is over 500 feet of elevation change, which required 103 locks on the Miami and Erie Canal. This is the only working lock in Ohio still used by a canal boat.