Kaanapali Beach is on the West side of Maui, and is in the lee of the trade winds. The islands of Molokai and Lanai (visible offshore) form an area of protected water that is a nursing ground for Humpback whales.
The old pier at Black Rock is near the Maui Eldorado Beach Cabana and marks a great location to enter the water for snorkeling around Black Rock. Often when snorkeling around Black Rock you will hear whale song.