Maui is a leading whale-watching center in the Hawaiian Islands due to Humpback whales wintering in the sheltered Auau Channel between the islands of Maui county. The whales migrate approximately 3,500 miles (5,600 km) from Alaskan waters each autumn and spend the winter months mating and birthing in the warm waters off Maui, with most leaving by the end of April. The whales are typically sighted in pods: small groups of several adults, or groups of a mother, her calf, and a few suitors. Humpbacks are an endangered species protected by U.S. federal and Hawaii state law. There are estimated to be about 18,000 humpbacks in the North Pacific. Although Maui’s Humpback face many dangers, due to pollution, high speed commercial vessels, and military sonar testing, their numbers have increased rapidly in recent years, estimated at 7% growth per year.
Maui is home to a large rainforest on the northeastern flanks of Haleakalā, which serves as the drainage basin for the rest of the island. The extremely difficult terrain has prevented exploitation of much of the forest.
Agricultural and coastal industrial land use has had an adverse effect on much of Maui’s coastal regions. Many of Maui’s extraordinary coral reefs have been damaged by pollution, runoff, and tourism, although finding sea turtles, dolphins, and Hawai’i’s celebrated tropical fish, is still common.