Polihale is the place where the Na Pali on the North Shore starts. Notice the Makaha Ridge Tracking Station (white dot on the cliff top) in this view.
The drive from the town of Mana to Polihale is along a sandy dirt road that is best taken slowly even in a rental car. There are some lush tropical landscapes here, as well as the famous Queen's Pond bathing hole. This is part of the Mana Plain, which is composed of lagoon deposits, dune sand and alluvium, with an ancient sea cliff further inland.
From here you can continue on to Stop 2 on the ground, or you can pick another point from the Kauai Virtual Field Trip page.