The Flat Islands are in Cook Inlet at the entrance to Kachemak Bay, about 1 mile (1.6 km) offshore from the Kenai Peninsula and 13 miles (21 km) southwest of Seldovia, Alaska. The presumably descriptive name was given by William Healey Dall of the U.S. Coast and Geodetic Survey in 1880.
The Flat Islands are treeless, grass-covered, and composed of two closely connected islands joined by bare reefs and surrounded by kelp. These islands form a good radar target that provides an important transit turn point used by large vessels. The Flat Island Light is on a skeleton tower, 70 feet (21 m) above the water, with a red and white diamond-shaped daymark on the northwest point of the northernmost island. Flat Island is also the location of a Coastal-Marine Automated Network (C-MAN) weather station.
C-MAN weather stations are part of a meteorological observation network along the U.S. coast. The network consists of about 60 stations installed on lighthouses, at capes and beaches, on nearshore islands, and on offshore platforms. The stations record atmospheric pressure, wind direction, speed and gust, and air temperature. Some are designed to also measure sea surface temperature, water level, waves, relative humidity, precipitation, and visibility. The network is maintained by the National Data Buoy Center of the National Weather Service, which is part of the National Oceanic and Atmospheric Administration. Data from the C-MAN stations are telemetered and ingested into numerical weather prediction computer models. Read more here and here. Explore more of the Flat Islands here: