When visiting Waimea Canyon in northwest Kauai it's almost hard not to notice two-tier Waipo'o Falls dropping some 800ft into the Canyon below. You're first glimpse of the falls is at the Waimea Canyon Overlook, past mile marker 10 on Highway 550. Both the canyon and the falls are spectacular from this lookout (seen below). Further up the road at Pu'u Ka Pele lookout, near mile marker 13, you can get your closest (though partially obstructed) view of the falls from Highway 550. You're still a remarkable distance away from the falls, but it's a beautiful photo opportunity.
If you're looking to hike to the falls, you're in luck, sorta. The Canyon Trail is a moderate trail that begins between the 14 and 15 miles markers. It takes you to the top of Waipo'o Falls, and it considered one of the premier trails of Koke'e State Park. The only downside (that 'sorta' we mentioned) is that once you reach the end of the hike, you can't really see the falls beneath you - though the Canyon views are phenomenal. The only reward, water-wise, at the end of this hike are the pools above the falls. The best way to get a really up close view of the falls is via a helicopter tour. Many tours take you right up to the falls and you can snap an up-close photo (seen above). The flow rate of the falls depends on precipitation like most falls in the islands. The falls often go completely dry in the summer when less rain frequents the islands. During the winter months, or after a good rain however, the falls are most impressive.