 The French term presqu 'île , the origin of the park 's name , means " peninsula " , or , literally , " almost an island " . Despite the name , Presque Isle has been an island for brief periods of time after it has been cut off from the mainland several times since 1819 — the longest stretch was from 1832 to 1864 . In the 1950s to combat erosion , the state and federal governments built sets of concrete seawalls and perpendicular groins . In 1992 , a series of 58 breakwaters were also constructed to have capture sand and significantly slowed its movement eastward . Even with the substantial engineering projects , sand has to be relocated from tombolos that form behind the breakwaters , and new sand has to be brought in annually to replenish the beaches . 
