One challenge in building a canal is that water levels are different from one place to the next. To let boats move between high and low levels, a canal has locks, or sections of water held between two gates. It’s like an elevator for boats. One gate opens, water flows in or out, and the boat is lifted or lowered to the level of the water in the next lock. Then the second gate opens, and the boat moves forward.

One challenge in building a canal is that water levels are different from one place to the next. To let boats move between high and low levels, a canal has locks, or sections of water held between two gates. It’s like an elevator for boats. One gate opens, water flows in or out, and the boat is lifted or lowered to the level of the water in the next lock. Then the second gate opens, and the boat moves forward.

One challenge in building a canal is that water levels are different from one place to the next. To let boats move between high and low levels, a canal has locks, or sections of water held between two gates. It’s like an elevator for boats. One gate opens, water flows in or out, and the boat is lifted or lowered to the level of the water in the next lock. Then the second gate opens, and the boat moves forward.