Hawaiian Trough the Hawaiian Arch. The Hawaiian Arch extends about 200 meters above the surrounding ocean floor, and contains tilted coral reefs. The coral reefs in the Hawaiian Tough are described as mesophotic coral ecosystems, which can be found between 100 and 500 feet below sea level. 43 percent of fish species documented at the mesophotic reefs are unique to the Hawaiian Islands. At Maui’s ‘Au’au channel the largest uninterrupted mesophotic coral ecosystem was discovered, with an area larger than 3 square miles. These reefs contained many stony, reef building coral that belong to the genus Leptoseris, which are adapted for deep
Geography of the Marquesas Islands clustered around the main island of Hiva `Oa. With a combined land area of 1,274 km² (492 sq. miles), the Marquesas are among the largest island groups of French Polynesia, Nuku Hiva being the second largest island in the entire territory, after Tahiti. With the exception of Motu One, all the islands of the Marquesas are of volcanic origin. In contrast to the common perception of lush tropical vegetation that goes culturally hand-in-hand with the appellation "Polynesia", the Marquesas are remarkably dry islands. Although the islands lie within the tropics, they are the first major break in the prevailing easterly