The North Cascades...
is the area I have spent the least amount of time in. Always on my list, the National Park in this area is said to be the "American Alps". The areas I have personally been around the most are the Mountain Loop Highway and the Mount Baker Wilderness. I have driven through North Cascades National Park a few times but have only been to a very small portion including the Ross Lake area which is breathtaking, to say the least. With the Boulder River Wilderness, Glacier Peak Wilderness, Lake Chelan-Sawtooth Wilderness, Mount Baker Wilderness, Pasayten Wilderness, and of course, North Cascades National Park, Ross Lake, and Lake Chelan National Recreation Area there are definitely more adventures to be had! Until then, I hope you enjoy what I have captured.
For first time visitors, my off the top of my head suggestions would be to visit Diablo Lake and take the beautiful North Cascades Scenic Highway (Highway 20) to get the chance to really see the scale of these impressive peaks. This magical highway can lead you to many hikes within the National Park and beyond. Link to this a good handful of this area's hikes is below!
FUN FACT: The North Cascades National Park has more glaciers than anywhere else in the United States besides Alaska. (over 300!)
Explore the North Cascades:
Below are just general resources to help you find your next adventure. This is really just the tip of the iceberg but I hope it helps. If you are looking for backpacking info search for the Backcountry Wilderness Map on the NPS website.