The Hawaiian Islands Humpback Whale National Marine Sanctuary is one of the world's most important whale habitats, hosting thousands of humpbacks (Megaptera novaeangliae) each winter.

The sanctuary encompasses 1,400 square miles (3,600 km2) in the islands' waters. It was designated by United States Congress on November 4, 1992, as a National Marine Sanctuary to protect the endangered North Pacific humpback whale and its habitat The sanctuary promotes management, research, education and long-term monitoring.

With its boundaries including waters from the shoreline to depths of 600 feet (180 m) in many areas, the sanctuary encompasses a variety of marine ecosystems, including seagrass beds and coral reefs. Much of the sanctuary has fringing coral reefs close to shore and deeper coral reefs offshore. Hawaii's coral reefs are noted for their isolation. Over 25% of all Hawaii's reef animals are endemic, found nowhere else on Earth.[4]

The Hawaii sanctuary is unlike any other National Marine Sanctuary in that it targets a single species, relies entirely on other agencies for enforcement, and has no protective rules such as no-go zones or no-wake zones or no-take zones that are specific to the sanctuary. It even allows permitted dumping of ship waste within its borders.

Almost two-thirds of North Pacific humpback whales (estimates range from 4,000 to 10,000 whales) migrates to Hawaiian waters each winter to bear and nurse their calves and to mate, although not to eat. They can cover nearly 3,000 miles (4,800 km) of open ocean in less than two months' time This population is growing an estimated 7% per year, but is still greatly diminished from the estimated 15,000 to 20,000 in the days before the whaling ban.

In 1966 the International Whaling Commission (IWC) put them in a protected status worldwide, outlawing whaling, but large illegal kills continued into the 1970s. Currently humpbacks are thought to number about 30,000–40,000 worldwide, which is approximately 30–35 percent of their pre-whaling population.

Compared to other whales, the humpback whale has extremely long flippers which reach up to 30 percent of its length of up to 40 feet (12 m). The whale appears dark from the top while its flippers and tail, the sides and underside appear partially white and are noticeable when they are beginning dive as are their small dorsal fins. Male humpback whales produce vocalizations described as "songs" over 10-20 minute periods. Whales in different areas of the world sing different songs, but those in the same area sing the same song. A song can be repeated for hours. They change slightly from year to year. The whales engage in many other interesting behaviors that can be observed from shore.