Awash at half tide, in Palma Bay 0.6 km (0.4 mi) southwest of Boussole Head, in Glacier Bay National Monument, 92 km (57 mi) west-northwest of Hoonah, Saint Elias Mountains.
HistoryNamed in 1926 by U.S. Coast and Geodetic Survey (USC&GS), for the lighthouse tender Alder which struck this rock.
Astrolabe Rocks, Graves Rocks,
Bars:Bays:Astrolabe Bay, Boussole Bay, Dixon Harbor, Graves Harbor, Murk Bay, Murphy Cove, Palma Bay, Thistle Cove, Torch Bay,
Capes:Astrolabe Peninsula, Astrolabe Point, Eerie Point, Eerie Point, Hankinson Peninsula, Icy Point, Venisa Point,
Glaciers:Brady Glacier, Finger Glacier,
Islands:Libby Island, Sugarloaf Island,
Lakes:North Deception Lake, North Trick Lake, South Deception Lake,
Mountains:Boussole Head, De Langle Mountain, Horn Mountain, Mount La Perouse, Mount Marchainville,
Rivers:Streams: