Martha's Vineyard is around the same size as Mammoth Cave National Park.

Mammoth Cave National Park is approximately 219 km² (84 sq mi), while Martha's Vineyard is approximately 227 km² (87 sq mi), making Martha's Vineyard 4% larger than Mammoth Cave National Park.
Tip: This to-scale comparison of Mammoth Cave National Park vs. Martha's Vineyard uses the Mercator projection, which distorts the size of regions near the poles.

Compare further: Martha's Vineyard vs. Mammoth Cave National Park

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