There are national parks for every kind of traveler—hikers, Instagrammers, rock climbers, slackliners—but if you're into butterflies, head to Sanjay Gandhi National Park in Mumbai. According to National Geographic Traveler, there are more butterfly species found in this 40 square miles than there are in all of the United Kingdom.
In 2015, The Hindustan Times reported that there were 172 species living in the park, 100 of them being rare butterflies. (The United Kingdom has 60 species.) For the best views, head to the Butterfly Garden. The park shares that it's in its prime from September to January, so plan your trip accordingly.
The most common butterflies you'll see are the Common Crow Butterfly, the Common Tiger, Blue Tiger, Gray Pansy, the Common Jezebel, the Dark-branded Bushbrown, the Common Emigrant, the Red Pierrot, the Tailed Jay, the Great Orange-tip, the Peacock Pansy, and the Gaudy Baron.
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The park created a booklet called Butterflying in SGNP for visitors that helps them identify the rare insects with illustrations and information about each species. For more information on the butterflies you can see at Sanjay Gandhi National Park, head to its website.