Chatham Seaplane Base (IATA: CYM, FAA LID: CYM) is a privately owned, public use seaplane base located in Chatham in the U.S. state of Alaska.

[1] Chatham lies within the limits of the City and Borough of Sitka, Alaska (near its northeast corner).

Chatham Seaplane Base has one seaplane landing area designated NW/SE with a water surface measuring 10,000 by 1,000 feet (3,048 x 305 m).

For the 12-month period ending December 31, 2006, the airport had 85 aircraft operations, an average of 7 per month: 94% air taxi and 6% general aviation.

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