Wachusett Reef is a phantom reef in the Antarctic Ocean.
Captain Lambert of the ship Wachusett reported that on June 4, 1899, he passed over a reef which appeared to be of coral formation in approximately latitude . The reef appeared to be about wide. The bottom showed of a dark gray color with deep blue on both sides of the reef. The depth was estimated at from ; unfortunately no soundings were taken.
The 2015 edition of the National Geographic Atlas of the World still shows Wachusett Reef, with a depth of . Nevertheless, its existence is doubtful, making it a phantom reef. Other nearby historically reported reefs which appear to not exist include Ernest Legouve Reef, Jupiter Reef, and Maria Theresa Reef.