2015 large lock maintenance, Hiram M. Chittenden Locks, Seattle, Washington. Looking east through the opening between lock gates at new plastic seals for the lock gates. We are looking past the normal lower (seaward) gate of the locks; the gate in view is at the middle of the large lock, and is regularly used to allow a use of the lock at half size; the full lock is used only for very long ships. Behind us, another gate (the only one with the opposite mitre) provides the seal for pump-out.