In an archipelago like the Hawaiian Islands the water between islands is typically called a channel or passage. Described here are the channels between the islands of Hawaiʻi, arranged from northwest to southeast.
The ʻAlenuihāhā separates the island of Hawaiʻi and the island of Maui. The maximum depth of this channel is 6100 feet (1900 m), and the channel is 30 miles wide. There is a significant wind funnel effect in the channel, which is subject to scientific investigations. ʻAlenuihāhā means "great billows smashing."
The ʻAlalākeiki Channel separates the islands of Kahoʻolawe and Maui, at a distance of 7 miles. ʻAlalākeiki means "crying baby."
The Kealaikahiki Channel is the channel between Lānaʻi and Kahoʻolawe. It literally means "the road to Tahiti"; if one takes a bearing off of Kealaikahiki Point on Kahoʻolawe while in the channel and heads directly straight, one arrives, more or less, in Tahiti. In practice, however, Polynesian navigators probably did not quite ply a straight route to Tahiti. The channel is 17 miles wide.
The ʻAuʻau Channel is one of the most protected areas of ocean in the Hawaiian Islands, lying between Lānaʻi and Maui. The channel is also protected by Molokaʻi to the north, and Kahoʻolawe to the south. The depth of the channel reaches 108 feet (33 m), and its width is 8.8 miles (14.2 km). ʻAuʻau channel is a whale-watching center in the Hawaiian Islands. Humpback whales migrate approximately 3,500 miles (5600 km) from Alaskan waters each autumn and spend the northern hemisphere winter months in the protected waters of the channel.
ʻAuʻau translates to "to take a bath" referring to its calm bath-like conditions.
The middle of the ʻAuʻau channel off Lahaina is known as the Lahaina Roads. Once filled with whalers when Lahaina was a capital for that industry, Lahaina Roads were later adopted as an alternate anchorage for the main U.S. Pacific Fleet based at Pearl Harbor. In the planning for the attack on Pearl Harbor, the Japanese had hoped that the Pacific Fleet still utilized Lahaina as an anchorage as ships sunk in the deep water there would have been unrecoverable. However, Lahaina was not utilized, and the bulk of the fleet remained moored in Pearl Harbor. The Roads are still a common moorage for oceangoing cruise ships and naval vessels of many flags, including the U.S., whose crews enjoy liberty on the island.