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Like other coastal areas along the Gulf of Maine , it experiences moderately high tides , and thus the water level in the estuary and the harbor varies greatly throughout the day , leaving mud flats at low tide .
 Gulf of Maine
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 Gulf of Maine