National Highway 66, commonly referred to as NH 66 (erstwhile NH-17 and a part of NH-47), is a busy National Highway that runs roughly north–south along the western coast of India, parallel to the Western Ghats. It connects Panvel (a city south of Mumbai) to Cape Comorin (Kanyakumari), passing through the states of Maharashtra, Goa, Karnataka, Kerala and Tamil Nadu.
It starts at Panvel, at the junction of National Highway 4 (NH 4), and ends at Kanyakumari. NH-66 mainly traverses through the west coast of India, sometimes touching the shores of the Arabian Sea. The NH66 touches the Arabian Sea at Maravanthe in Karnataka, Thalassery, Alappuzha and Kollam in Kerala. It passes through the Indian states of Maharashtra, Goa, Karnataka, Kerala and Tamil Nadu.
Knowledge source : wikipedia