At the west end of Ballard , Hiram M. Chittenden Locks (N.W. 54th St., 206/783-7059, www.nws.usace.army.mil , 7 a.m.–9 p.m. daily) connect saltwater Puget Sound with freshwater Lake Washington via Lake Union . The Chittenden Locks (also known as the Ballard Locks) serve various functions: a passageway for some 90,000 ships each year, a way to prevent saltwater intrusion into the lakes, and a fish ladder.
Built between 1911 and 1917, the Chittenden Locks are managed by the U.S. Army Corps of Engineers, which has a visitors center (10 a.m.–6 p.m. daily mid-May to mid-Sept., and 10 a.m.–4 p.m. Thurs.–Mon. rest of the year) here. Films are shown here every half hour. Attend free hour-long guided tours every day at 1 p.m. and 3 p.m. in the summer, and on Saturday and Sunday at 2 p.m. in the winter months, or join the throngs and figure it out for yourself.
Chittenden Locks are one of Seattle’s  most-visited attractions; over a million people come here each year to watch container ships, tugs, tour boats, fishing boats, and pleasure craft make the transition between saltwater and freshwater. They also come to see the salmon return home to spawn via big underwater windows along the fish ladder—the best time to look for the salmon is late June to early September.
On the bank overlooking the Chittenden Locks are the Carl S. English Jr. Botanical Gardens, with more than 500 species of plants that English collected from around the world, plus native Northwest species. Included are pines, palms, oaks, dawn redwood, swamp flowers, and trees, and a great collection of rhododendrons. A brochure details a self-guided tour through the gardens.