The Betsimisaraka are the largest ethnic group on the island, though there had been a long history of mixed marriages, including with pirates in the 17th century.

Beginning with Adam Baldridge in 1691[4] and ending with John Pro in 1719, the location was favourable for pirate activity, being near maritime routes travelled by ships returning from the East Indies, their holds overflowing with loot.

Legendary pirates including William Kidd, Robert Culliford, Olivier Levasseur (La Buse) who wrote a cryptogram, Henry Every, Abraham Samuel and Thomas Tew lived in the île aux Forbans, an island located in the bay of Sainte Marie's main town, Ambodifotatra.

France left the settlement abandoned for roughly half a century until returning in 1818, when the island was converted into a penal colony.

On 7 May 2015, a large 55 kg (121 lb) "silver" ingot, which was believed to be Captain Kidd's treasure, was found off the coast of the island.

[8] After further analysis, UNESCO determined that the piece actually consisted of 95% lead; they judged it to be "a broken part of the Sainte-Marie port constructions.

The island was home to the only known population of Delalande's coua, a species of cuckoo that became extinct in the late 19th century, possibly due to predation by feral cats.

Nosy Boraha is the setting for the fantasy historical children's book Kintana and the Captain's Curse by Susan Brownrigg.