on W coast of Aialik Peninsula, 5 mi. NW of Aialik Cape, 26 mi. SW of Seward, Chugach Mts.
Named in 1909 by U. S. Grant, U.S. Geological Survey (USGS), "for the three prominent natural arches there."
Agnes Cove, Aialik Bay, Bear Cove, Bulldog Cove, Cataract Cove, Chat Cove, Cliff Bay, Coleman Bay, Crater Bay, Fire Cove, Holgate Arm, Lower Pedersen Lagoon, McMullen Cove, Paradise Cove, Pony Cove, Porcupine Cove, Quicksand Cove, Ripple Cove, Taz Basin, Three Hole Bay, Tooth Cove,
Capes:Aialik Cape, Aialik Peninsula, Bear Glacier Point, Callisto Head, Granite Cape, Holgate Head, Three Hole Point, Toe Point,
Channels:Cheval Narrows, Dora Passage, Granite Passage, Harding Gateway, Petes Pass,
Glaciers:Addison Glacier, Aialik Glacier, Glacier G210167E59798N, Lechner Glacier, Pedersen Glacier, Upper Pedersen Lagoon,
Hills:Islands:Beehive Island, Chat Island, Cheval Island, Chiswell Island, Dora Island, Frozen Rock, Granite Island, Harbor Island, Hub Rock, Lone Rock, Matushka Island, Natoa Island, No Name Island, Pilot Rock, Slate Island, Squab Island, Twin Islands, Twin Rocks, Verdant Island,
Lakes: