North of Lahaina and south of Napili on Maui, the Kaanapali Beach (aka Black Rock) is popular for snorkeling. The best Kaanapali Beach snorkeling is at the north end of this 3 mile long beach. The water ranges from 8 to 25 feet deep. Occasionally, green sea turtles come in to rest on the lava rock ledges. Keep an eye out for the porcupine fish, goat fish and box fish. The Black Rock is a lava wall with coral cover that is a nice dive wall for snorkelers (look for octopus). If you are going to snorkel out to Black Rock Point, make sure the water is calm and watch out for the very strong currents. If you're lucky, you'll spot a spotted eagle ray in the deep sands along the way.
If you arrive early, there are some free parking spaces at the Sheraton Maui Resort. Otherwise, you will need to park at the centrally located and quaint Whalers Village, whose stores offer parking validation with purchase.
For more details on Kaanapali Beach snorkeling, we highly recommend the Maui Snorkeling Guide eBook