Maro Reef

With a total area of 747 square miles (1,935 km2), it is the largest coral reef in the Northwestern Hawaiian Islands.

Located about 850 miles (740 nmi; 1,370 km) northwest of Honolulu, Hawaii, Maro Reef contains about 1 acre (4,000 m2) of dry land which itself can be submerged depending on the tides.

[1] USNS Mission San Miguel (T-AO-129) ran aground on the reef, while running at full speed and in ballast, and sank on October 8, 1957.

The ship was a Buenaventura class tanker built in WW2, and due to problems with LORAN reception (for navigation) miscalculated its location striking Maro reef.

At 523 feet long it is the largest ship lost on Maro reef and noted for historical significant as WW2 T2 tank vessel.

Satellite image of Maro Reef
Wreck of the USNS ship Mission San Miguel . All hands were evacuated before it sank in 1957. It was rediscovered in 2015
USCG image of an abandoned anchor in Maro Reef
Scheme of a Hawaiian eruption