A peninsula is a piece of land which is surrounded by water on three sides but connected to the mainland. India is called peninsula because it is surrounded by Bay of Bengal, Arabian sea and Indian ocean on the three sides but on the fourth side land locked by Himalayan mountains 

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A peninsula is a land bordered with water bodies around and it connected with a main land .
India is a peninsula as it is surrounded by the Bay of Bengal in the East,Arabian sea in the west and the Indian Ocean in the South of it except the northern part which is blocked by the Great Himalayan Range
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