Consider this a must-do if you are in Seattle and feel like knocking out two amazing hikes AND getting to see a hidden lake all along US 2.
The trail starts out on an old road with the typical amazing forest surrounding you. After roughly 2miles the road will end and you can go right (signage is easy to see) to Bridal Veil Falls or you can keep going and go straight to Lake Serene. This is where I would suggest going up to Bridal Veil since it's only an extra mile and totally worth it. Plus there's nothing like swimming under a waterfall.
Once back on the main trail you'll cross over a bridge, good place for a photo, and then start to climb. It will be a combo of stone steps, rocks and trail, but just be prepared to push (gaining 1300' in 1.5 miles). Along the way you will see a bunch of peaks in the Wild Sky Wildnerness.
At the top you will see the stunning Lake Serene and all its glory. There is a 3000 vertical foot wall that sits behind the lake, so venture around a little bit before stopping to each your snacks/ lunch. If you're up for it, don't hesitate to jump in! Go back down the same way you came and take it slow, you've done all the hard work already.