The 140 acre Polihale State Park is located at the end of Hawaii's biggest and perhaps most majestic beach, one that stretches for over 12 miles and includes sand dunes that reach 100ft high. This is the location of Kauai's famous Barking Sands. When large amounts of sand are moved the friction results in a sound resembling a barking dog (grains of sand here have microscopic holes and champers that cause resonating vibrations, but only when the sand is dry).
The beach starts in Kekaha but unfortunately a military base, the Pacific Missile Range Facility, occupies a 7 mile stretch. Strong currents at Polihale make for dangerous swimming conditions and during the winter months the area is subject to big north shore swells as seen in the below photos. The only safe place to swim (during calm seas) is an area known as the Queen's Pond, a reef protected section adjoining the beach. The panoramic photos below where taken in front of the pond but it's not visible due to high surf.
Preparations are required for a day trip to this hot region. Pack plenty of food and a beach umbrella if possible. The drive to the beach is via a 5 mile long poorly maintained dirt road. You may want to double check that your rental car agreement allows you to drive the road..