The second-largest lake in the North Cascades  after Lake Chelan , Ross Lake is 24 miles long and up to two miles wide, covering 12,000 acres from the Skagit River up to and beyond the Canadian border. It was created by a 540-foot-high hydroelectric dam completed in 1949 by Seattle City Light. Fortunately, efforts to enlarge the dam were thwarted in the 1980s by environmentalists and the government of British Columbia .
You can see the reservoir from the Ross Lake overlook at milepost 135 on Highway 20  or area hiking trails, but the only vehicle access and motorboat launch is at the lake’s north end, via a 39-mile gravel road from Canada. This means that Ross Lake is more of a canoeing and kayaking lake than other reservoirs in the Cascades. The glacier-fed waters of Ross Lake are too cold for swimming.
Although you can’t drive to Ross Lake Resort (206/386-4437, www.rosslakeresort.com , $122–261 d, $10 extra person) you can catch the Seattle City Light boat ($20 round-trip) that leaves the parking lot across Diablo Dam daily at 8:30 a.m. and 3 p.m. The tug takes you to the end of Diablo Lake , where a truck ($7 round-trip) carries you on to Ross Lake. This is one of the most unusual lodging places in Washington; everything here is literally on the water, with cabins and bunkhouses built on log floats.
Visitors can stay in modern cabins, rustic 1950s-era cabins, a 10-person bunkhouse, or nine-person cabins. Enjoy fantastic views up the lake to 8,300-foot Mt. Hozomeen at the Canadian border. You can rent motorboats, kayaks, or canoes here, but there are no telephones, groceries, or food service. The lodge is open mid-June through October.
Ross Lake has water-side campsites and half a dozen trailheads that provide access into adjacent North Cascades National Park . Ross Lake Resort runs a water taxi (206/386-4437) service to these, along with boat tours and portages from Diablo Lake  for small boats and canoes. The water taxi fares are by the boatload (it can hold six), not per person, so it’s best if you can coordinate your travel with other folks to save money. These water-taxi trips are a fun way to reach the backcountry, but be sure to pick up backcountry permits from the Wilderness Information Center in Marblemount  before heading out to camp along Ross Lake or hike in the backcountry.