From the Land Bank’s description:
The barrier beaches separating the Island’s south shore great ponds from the the sea are important habitats for wildlife … and unique destinations for adventurous humans, who enjoy the sites’ light, wind and sense of expansiveness. The Land Bank’s first acquisition of such land was in 1993 on the Chilmark Lower Pond; an acquisition on the Edgartown Great Pond followed in 1997. Tisbury Great Pond was the last of the three and was consummated in 2004.