Hui Dr, Lahaina HI 96761
There are two public beach accesses. The one at the south end of the bay is at Napili Place. The second access near the middle of the bay is at Hui Drive. Both have limited roadside parking. Alternatively, you can part at next door Kapalua Bay
which has a parking lot and walk to Napili Bay (there is a path along the shoreline). You'll also find a bathroom and showers near the Kapalua parking lot.