The trail begins at Lake Diablo, which is a magical, turquoise color -- but a bit too cold for swimming! The trail will take you through various landscapes, including Douglas firs and rainforest (plentiful ferns!), rocky areas, and really lovely views of the lake and surrounding majestic mountains. Along the way you will be rewarded with stunning views of Pyramid, Snowfield, Davis and Colonial Peaks, as well as Jack Mountain. The trail leads along the top of a gorge and from there you can see waterfalls and look down at the blue-green glacial waters of the lake. It's a nice, fairly easy hike with not too much elevation change, good for kids and for dogs (dogs aren't allowed on trails in North Cascades National Park, but they are allowed here -- the Diablo Lake Trail is actually in the Ross Lake National Recreation Area adjacent to the park boundary). Kayaking and canoeing are fun activities here, too, and there are camping possibilities. Colonial Creek, Thunder Point, and Hidden Cove campgrounds are all nearby. Diablo Lake is really worth a day trip if you are in Seattle area - the scenic drive from Seattle is also truly beautiful.