Multnomah Falls, which is the largest waterfall in Oregon, is located 30 miles East of Portland and makes for a great day trip outside of the city. In fact, it's such a great outing that 2 million people visit the waterfall every year.
To reach Multnomah Falls you'll want to drive East via the I-84 and take exit 31 for Multnomah. The parking lot is often at full capacity so you may need to turn around and head towards Rooster Rock (exit 25) for parking. From there you'll find a free bus that will take you to the entrance of Multnomah Falls.
From the entrance you can walk 1.2 miles up to the main viewpoint, which is pictured above. Once you've reached the main viewpoint you can relax, take pictures, and soak in the beauty of Oregon's largest and most famous waterfall.
Note: Many of the trails in this area were closed because of damage sustained during the 2017 Eagle Creek Fire. However, the trails are now open again as of June 2019. You can read about this recent announcement here.